Advances in AI for Protein Structure Prediction: Implications for Cancer Drug Discovery and Development

✅ 全文

人工智能在蛋白质结构预测中的进展:对癌症药物研发的影响

作者 Xinru Qiu; H. Li; Greg Ver Steeg; Adam Godzik 期刊 Biomolecules 发表日期 2024 ISSN 2218-273X DOI 10.3390/biom14030339 类型 原创研究 (Original Research)

📄 中文摘要 Chinese Abstract

中文
近期人工智能驱动技术的进展,特别是在蛋白质结构预测领域,正在深刻重塑药物发现与开发的格局。2021年AlphaFold2(AF2)的问世标志着一项突破性进展,它能够仅凭序列数据实现原子级别的精确蛋白质结构预测,解决了结构生物学中长期存在的难题。本综述探讨了此类AI工具——以及ESMFold、RoseTTAFold和OpenFold等其他工具——如何通过改善靶点识别、药物设计和疾病机制理解来推动癌症研究。同时,本文还审视了生成式AI在蛋白质工程和分子对接中的更广泛影响,并指出了当前局限性与未来发展方向。

📋 英文结构化总结 English Structured Summary

全文整理

EN

Background:

Recent advancements in AI-driven technologies, particularly in protein structure prediction, are significantly reshaping drug discovery and development. The introduction of AlphaFold2 (AF2) in 2021 marked a breakthrough by enabling accurate atomic-level protein structure prediction from sequence data alone, addressing a long-standing challenge in structural biology. This review explores how such AI tools—alongside others like ESMFold, RoseTTAFold, and OpenFold—are transforming cancer research by improving target identification, drug design, and understanding of disease mechanisms. It also examines the broader implications of generative AI in protein engineering and molecular docking, while highlighting limitations and future directions.

Methods:

N/A – Review article

Results:

AlphaFold2 has demonstrated high accuracy in predicting protein structures, especially when multiple sequence alignments (MSAs) are available, and has been applied to identify pathogenic mutations, predict protein–protein interactions (PPIs), and support virtual screening for drug candidates. For example, AF2 predicted structures of all human diacylglycerol kinase (DGK) paralogs, revealing conserved domains and ATP-binding sites, and helped model the VIPR2 receptor complex. ESMFold offers faster predictions without MSAs, making it suitable for orphan proteins, while RoseTTAFold extends capabilities to protein–nucleic acid complexes. OpenFold provides an open-source, retrainable version of AF2 with improved efficiency. Generative models like RFDiffusion and ProteinMPNN enable de novo protein design, and AI docking tools such as DiffDock enhance virtual screening precision.

Data Summary:

The AlphaFold Protein Structure Database contains over 200 million predicted structures, and the ESM Metagenomic Atlas includes more than 700 million predictions from microbial environments. In benchmark tests, AF2 achieved a mean GDT-TS score of 73.06, while ESMFold scored 61.62 but operates six times faster than AF2 on a single GPU. RoseTTAFold underperformed compared to ESMFold in over 80% of cases. OpenFold matches AF2’s accuracy and reaches 90% performance in just 3% of AF2’s training time. Studies using AF2 identified 1,798 potential cancer-related PPIs, with 1,087 lacking prior structural characterization.

Conclusions:

AI-driven protein structure prediction is revolutionizing drug discovery by accelerating target validation, enabling structure-based drug design, and facilitating the understanding of disease mechanisms at the molecular level. AlphaFold2 has catalyzed the development of diverse AI tools that collectively enhance various stages of the drug pipeline—from sequence generation to docking. Despite challenges related to computational demands, dynamic conformational changes, and data privacy, these technologies are streamlining development timelines and reducing costs. Their integration into workflows holds promise for improving success rates in clinical translation, particularly in oncology.

Practical Significance:

These AI tools have direct real-world applications in identifying novel drug targets (e.g., CDK20 in liver cancer), designing inhibitors (e.g., ISM042-2-048), predicting pathogenic variants (via AlphaMissense), and advancing personalized medicine. They are already being used in industry pipelines—such as Insilico Medicine’s AI-discovered drug INS018_055 for idiopathic pulmonary fibrosis, now in Phase II trials—and have contributed to rapid responses in global health crises like COVID-19 through accelerated antiviral discovery.

📋 中文结构化总结 Chinese Structured Summary

中文

背景:

近期人工智能驱动技术的进展,特别是在蛋白质结构预测领域,正在深刻重塑药物发现与开发的格局。2021年AlphaFold2(AF2)的问世标志着一项突破性进展,它能够仅凭序列数据实现原子级别的精确蛋白质结构预测,解决了结构生物学中长期存在的难题。本综述探讨了此类AI工具——以及ESMFold、RoseTTAFold和OpenFold等其他工具——如何通过改善靶点识别、药物设计和疾病机制理解来推动癌症研究。同时,本文还审视了生成式AI在蛋白质工程和分子对接中的更广泛影响,并指出了当前局限性与未来发展方向。

方法:

不适用——综述类文章

结果:

AlphaFold2在蛋白质结构预测中展现出高准确性,尤其在可获得多序列比对(MSAs)的情况下,已被用于识别致病突变、预测蛋白质-蛋白质相互作用(PPIs)以及支持候选药物的虚拟筛选。例如,AF2预测了所有人类二酰甘油激酶(DGK)旁系同源物的结构,揭示了保守结构域和ATP结合位点,并帮助构建了VIPR2受体复合物模型。ESMFold无需MSA即可实现更快的预测,适用于孤儿蛋白;RoseTTAFold将能力扩展至蛋白质-核酸复合物;OpenFold提供了AF2的开源可重训练版本,效率更高。RFDiffusion和ProteinMPNN等生成模型支持从头蛋白质设计,而DiffDock等AI对接工具提升了虚拟筛选的精度。

数据概要:

AlphaFold蛋白质结构数据库包含超过2亿个预测结构,ESM宏基因组图谱则包含来自微生物环境的超过7亿个预测结果。在基准测试中,AF2的平均GDT-TS得分为73.06,ESMFold得分为61.62,但在单块GPU上运行速度是AF2的六倍。在超过80%的案例中,RoseTTAFold表现不及ESMFold。OpenFold与AF2精度相当,且仅需AF2训练时间的3%即可达到90%的性能。利用AF2的研究已鉴定出1,798个潜在的癌症相关PPIs,其中1,087个此前缺乏结构表征。

结论:

AI驱动的蛋白质结构预测正在通过加速靶点验证、实现基于结构的药物设计以及在分子层面促进对疾病机制的理解,从而革新药物发现。AlphaFold2催生了多种AI工具的发展,这些工具从序列生成到对接环节共同提升了药物研发管线的各个阶段。尽管面临计算需求、动态构象变化和数据隐私等方面的挑战,这些技术正在缩短开发周期并降低成本。将其整合到工作流程中有望提高临床转化的成功率,尤其在肿瘤学领域。

实际意义:

这些AI工具在现实世界中具有直接应用价值,包括识别新型药物靶点(如肝癌中的CDK20)、设计抑制剂(如ISM042-2-048)、预测致病性变异(通过AlphaMissense)以及推动个性化医疗发展。它们已被应用于工业研发管线——例如英矽智能发现的AI药物INS018_055用于治疗特发性肺纤维化,目前已进入II期临床试验——并在新冠疫情等全球健康危机中通过加速抗病毒药物发现做出了快速响应。

📖 英文全文 English Full Text

EN

2397 biomol Biomolecules Biomolecules Multidisciplinary Digital Publishing Institute (MDPI) PMC10968151 10968151 10968151 38540759 10.3390/biom14030339 Advances in AI for Protein Structure Prediction: Implications for Cancer Drug Discovery and Development Qiu Xinru 1 Li Han 2 Ver Steeg Greg 2 Godzik Adam 1 * Paiardini Alessandro Academic Editor 1 Division of Biomedical Sciences, School of Medicine, University of California Riverside, Riverside, CA 92521, USA; xinru.qiu@ucr.edu 2 Department of Computer Science and Engineering, University of California Riverside, Riverside, CA 92521, USA; han.li001@email.ucr.edu (H.L.); greg.versteeg@ucr.edu (G.V.S.) * Correspondence: adam.godzik@medsch.ucr.edu 12 3 2024 14 3 339 339 28 3 2024 © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( https://creativecommons.org/licenses/by/4.0/ ). Abstract Recent advancements in AI-driven technologies, particularly in protein structure prediction, are significantly reshaping the landscape of drug discovery and development. This review focuses on the question of how these technological breakthroughs, exemplified by AlphaFold2, are revolutionizing our understanding of protein structure and function changes underlying cancer and improve our approaches to counter them. By enhancing the precision and speed at which drug targets are identified and drug candidates can be designed and optimized, these technologies are streamlining the entire drug development process. We explore the use of AlphaFold2 in cancer drug development, scrutinizing its efficacy, limitations, and potential challenges. We also compare AlphaFold2 with other algorithms like ESMFold, explaining the diverse methodologies employed in this field and the practical effects of these differences for the application of specific algorithms. Additionally, we discuss the broader applications of these technologies, including the prediction of protein complex structures and the generative AI-driven design of novel proteins. Keywords: AlphaFold2, cancer, drug discovery, artificial intelligence, generative AI status released display-pdf yes is-olf no is-manuscript no is-preprint no is-journal-matter no is-scanned no is-retracted no Received 2024 Jan 30; Revised 2024 Mar 4; Accepted 2024 Mar 6; Collection date 2024 Mar. 1. Introduction ChatGPT, DALL-E, and other tools, driven by recent revolutionary advances in Artificial Intelligence (AI) technology, have captured widespread attention due to the expanding capabilities of AI, with the promises and potential threats they bring to our society. However, AI-driven breakthroughs in various scientific fields have been in progress for some time. This review delves into a remarkable transformation within structural biology, catalyzed by the introduction of the AlphaFold2 (AF2) deep neural network algorithm in 2021 and followed by other algorithms. Together, these tools have effectively resolved a long-standing challenge in structural biology: the generation of atomic-level models for protein structures from sequence information alone [ 1 , 2 , 3 ]. This review seeks to investigate the extent to which these breakthroughs in protein structure prediction have influenced the drug discovery process, with an initial focus on cancer research, and also discuss how choices in the architecture and assumptions made by specific algorithms affect and differentiate their results. The process of drug discovery is frequently marked by inefficiency, underscored by rising expenses, prolonged timeframes, and a high frequency of failures. Only a small fraction of drug candidates make it to clinical trials, and many fail as late as in Phase 3, resulting in an overall success rate of about 10–20% in clinical drug development [ 4 ]. Estimations of the overall expenses for research and development prior to product launch range from $161 million to $4.54 billion in 2019 U.S. dollars per successful drug [ 5 ] ( Figure 1 ). This ineffectiveness is, in part, due to our incomplete understanding of human biology, especially in the context of disease processes; a dearth of actionable targets for treatment; and our limited understanding of the varied responses to disease in diverse populations [ 6 ]. Further complicating this process is the inadequacy of preclinical models that accurately represent the disease and the constraints of overly simplistic disease models, which together amplify the difficulties in grasping the complexity of human systems. Lack of high quality structural models of drug targets, a main problem addressed by AlphaFold, is only one of the challenges in drug discovery. However, as we show in this review, AI is also making rapid progress in addressing other bottlenecks in drug development. Figure 1 Stages of Drug Discovery Process: The drug discovery process comprises several critical stages. It begins with the “Discovery and Development” phase, where the focus is on target identification and validation. This stage involves screening potential compounds and further refining promising candidates through hit-to-lead development and lead optimization. Following this, the process moves to “Preclinical Development”, which includes a range of lab tests such as in vitro studies, animal model testing, and ADMET (Absorption, Distribution, Metabolism, Excretion, Toxicity) studies. Based on these results, a decision is made on whether to proceed to the next phase. “Clinical Trials” ensue, which are categorized into four phases: Phase I assesses safety and dosage; Phase II examines efficacy and side effects; Phase III involves larger studies to confirm efficacy and monitor adverse reactions; and the final stage is “Review and Approval”, which consists of a comprehensive regulatory review, culminating in market authorization and followed by post-marketing monitoring to ensure long-term safety and effectiveness, constituting a newly defined Phase IV. Traditionally, the three-dimensional structures of proteins are deciphered using labor-intensive and costly experimental methods like X-ray crystallography, nuclear magnetic resonance (NMR), and cryogenic electron microscopy (cryo-EM). While invaluable, these techniques are limited by speed, cost, and applicability to only certain protein structures. In contrast, recent advancements in protein structure prediction, culminating in AF2, have dramatically expanded our capabilities, complementing and occasionally surpassing experimental approaches. The AF2 breakthrough has been quickly followed by other AI tools such as RoseTTAfold [ 7 ], ESMFold [ 8 ], and OpenFold [ 9 ]. ProGen [ 10 ], ProteinMPNN [ 11 ], EvoDiff [ 12 ], and RFdiffusion [ 13 ] extend the AI capabilities to novel protein design, as does DiffDock [ 14 ] to molecular docking. These and many other rapidly developing tools apply novel algorithms and AI architectures, each with unique strengths and weaknesses. Here we focus not so much on the comparison of their predictions, but on the differences in their algorithms and approaches and the resulting optimal applications. 2. Protein Structure Prediction In Silico before AlphaFold In the period preceding the advent of AlphaFold, the process of protein structure prediction generally encompassed several distinct stages, as outlined in the following discussion ( Figure 2 ). Figure 2 Stages of Protein Structure Prediction: The foundational stage involves determining the DNA sequence that encodes the protein of interest. The next step is to infer the protein sequence from the DNA sequence. Homology modeling uses known protein structures as templates to predict the structure of a protein with an unknown structure but similar sequence. Lastly, validation of structure ensures the predicted structure’s biological plausibility. This involves checks on stereochemical quality, energy evaluation, and comparison to known structural data. 2.1. Homology and Comparative Modeling Homology modeling predicts a protein’s 3D structure using the structure of a homologous protein. It involves four steps: identifying a homologous protein with a known structure (target identification), aligning the target with the template sequence (alignment), constructing a model of the target protein from aligned regions (model building), and enhancing the model’s accuracy and stability (model refinement). Improvements in distant homology recognition and alignment between distant homologies are exemplified by the HHpred algorithm and the accompanying suite of programs [ 15 , 16 ]. Predictions of protein contact maps from coevolution patterns approached this problem from another angle [ 17 ], enhanced by the first applications of deep learning neural networks [ 18 ]. In the late 2010s tools such as Rosetta [ 19 ] and I-Tassser [ 20 ] crossed the line from homology to comparative modeling [ 21 ]. Rosetta achieved this by using smaller elements of known structures and a combination of energy-like scoring function and empirical folding rules. I-TASSER (Iterative Threading ASSEmbly Refinement)’s similarity uses a combination of template-based modeling and fragment assembly. Other tools’ similarity has started approaching the level of ab-initio protein structure prediction [ 21 ]. These advances directly led to the development of AlphaFold and the following AI approaches to protein structure prediction. 2.2. Structure Validation Structure validation ensures that the predictions are accurate and plausible. Tools like [ 22 ] analyze the geometry of structural features and verify the dihedral angles in the Ramachandran plot. Energy based evaluations, such as ANOLEA [ 23 ], assess potential energy to evaluate the correctness of folding. Finally, predicted structures can be compared to the experimental data, if such are available. Such comparisons can be used to benchmark the prediction methods and establish expected accuracy, but cannot be used to evaluate predictions for proteins with no known experimental structures. However, functional predictions based on the predicted 3D structures, such as identity of active site or interaction interface residues, can be tested in vitro, thus indirectly confirming the structure prediction. 3. Existing Protein Structure Data Sets and Their Applications Existing protein structure data sets play a pivotal role in protein bioinformatics ( Table 1 ). Protein structures elucidated through experimental methods by various structural biology research groups are submitted to the Research Collaboratory for Structural Bioinformatics (RCSB) Protein Data Bank (PDB) [ 24 ]. The practical applications of AI-based structure predictions have been made much easier by the development of the AlphaFold Protein Structure Database, which offers precalculated predictions for over 200 million protein structures. Integration of the AlphaFold2 and the UniProt databases extended access to protein structural information to a broad community of biologists [ 25 , 26 ]. The ESM Metagenomic Atlas contains predictions for over 700 million protein structures from various microorganisms found in environments such as soil, seawater, and the human gut. This comprehensive collection of predicted structures provides valuable insights into the metagenomic landscape [ 8 ]. These data sets collectively support a broad range of research studies and applications, including developing and evaluating machine learning models, advancing our understanding of protein biology, and facilitating drug discovery efforts. Table 1 Publicly available protein structure data sets and their applications in different phases of drug discovery. Resource Utility Data Repository and Reference Protein Data Bank (PDB) Provides 3D structures of proteins, nucleic acids, and complex assemblies which can be used for drug target identification, ligand design, and understanding protein–ligand interactions. RCSB PDB [ 27 ] AlphaFold Protein Structure Database Contains protein structure predictions for entire proteomes of several organisms. It can be used for target identification and understanding protein function. AlphaFold DB [ 25 , 26 ] CASP (Critical Assessment of protein Structure Prediction) Hosts protein structure prediction models from the CASP competition, useful for evaluating and improving structure prediction methods. CASP [ 28 ] SWISS-MODEL Repository A database of annotated 3D protein structure models generated by the SWISS-MODEL homology-modeling pipeline, useful for structure prediction and drug design. SWISS-MODEL [ 29 ] ESM Metagenomic Atlas The ESM Metagenomic Atlas displays more than 700 million predicted protein structures from microorganisms in environments like soil, seawater, and the human gut, accessible through an interactive page. ESM Atlas [ 8 ] 4. Disease Understanding—Examples of the Applications of AI-Based Structure Predictions Understanding Pathogenic Mutations AF2 protein structure predictions can help identify pathogenic missense variations in hereditary cancer genes. In a study by Karakoyun et al. [ 30 ], AF2-predicted structures and five protein stability predictors were used to evaluate the pathogenicity of more than a thousand missense variants from ClinVar and a breast cancer patient cohort. Their findings indicated that protein stability predictors show moderate effectiveness in identifying pathogenic variants. However, the AF2 confidence score, pLDDT, demonstrated a superior ability to predict pathogenicity, highlighting AF2’s potential in pinpointing genetic variations linked to cancer. AF2 can also help us understand the role of the paralogs of disease proteins. For example, dysfunction of human diacylglycerol kinase (DGK) is linked to multiple diseases, including cancer and autoimmune disorders. However, the exact mechanism of how DGK dysfunction contributes to the development of these diseases is not fully understood due to the lack of high-resolution structures for any of the 10 human DGK paralogs. In a recent study [ 31 ], the researchers used AF2 to predict the three-dimensional structures of all the human DGK paralogs and conducted structural alignment of the predictions to reveal the conserved domains and their spatial arrangement relative to each other. The study also used docking studies to corroborate the existence of a conserved ATP-binding site between the catalytic and accessory domains and to investigate the spatial arrangement of DGK with respect to the membrane. AF2 can aid drug discovery by accurately predicting protein 3D structures and identifying potential allosteric binding sites. Allosteric drugs, which bind the allosteric rather than the active sites, can induce conformational changes in proteins, affecting their activities. This enables the design of more effective drugs that can synergize with traditional orthosteric drugs to enhance efficacy. A study from Nussinov, R., et al. [ 32 ] illustrated how allosteric drugs can alter the conformation of an active site that a drug-resistant mutation has created, permitting a blocked orthosteric drug to bind. This suggests that a combination of allosteric and orthosteric drugs can be more effective than either drug type alone. In another study from Weng, Y., et al. [ 33 ], AF2 was used to predict the protein structure of WSB1. The predicted structure was then optimized using molecular dynamics simulations and validated using software. After that, virtual screening was performed using AutoDock-GPU and Glide to filter compounds using ligand- or structure-based methods. Finally, four compounds with different compound scaffolds were selected as potential inhibitors of WSB1. In a recent development, AlphaMissense, a computational tool devised by Google DeepMind, was shown to correctly assess the pathogenic potential of missense variants [ 34 ]. By utilizing the structural insights from AlphaFold, AlphaMissense evaluates the effects of mutations on the functionality of proteins. In the realm of cancer drug discovery, this tool holds significant promise in aiding researchers to efficiently select genetic mutations for in-depth study. This could expedite the process of identifying novel drug targets. Furthermore, AlphaMissense has the potential to enhance our comprehension of less-explored segments of the genetic code, especially genes that play crucial roles in human health but whose functions are yet to be fully understood. 5. Target Identification The next step after understanding the molecular mechanism of disease is identifying targets for therapeutic intervention. Again, knowledge of the structure of proteins involved in pathways or networks mutated or modified in cancer is an important step in identifying best drug targets. Understanding the molecular mechanisms of disease at the molecular level, including the functional, interactive, and mechanistic implications of gene product alterations, is essential for developing targeted therapeutic strategies for cancer. By modeling these aspects, researchers can evaluate and compare different strategies to correct the adverse outcomes caused by gene mutations. Such molecular models are instrumental in the design of effective cancer therapies [ 35 ]. 5.1. Prediction of Structures of Protein Complexes Accurate prediction of protein complex structures is vital for cancer drug discovery, offering insights into the molecular mechanism of signal transduction (where physical interactions between up- and down-stream elements of the signaling pathway are used to pass on the signal) or indirect mutation effects (when a mutation in another element of the complex is modifying the function of a critical protein). Structure-based approaches are instrumental in developing specific and effective drugs, as well as in addressing drug resistance issues. They also support personalized treatments by identifying unique vulnerabilities in cancer cells of specific patients and aid in minimizing drug side effects and interactions. In a study by Zhang, J., et al. [ 36 ], AF2 was used to predict the structures of protein complexes involved in cancer protein–protein interactions (PPIs). The researchers utilized AF2 to explore the protein–protein interactome associated with cancer, identifying 1798 potential protein–protein interactions (PPIs) related to cancer driver proteins. These proteins play roles in various cellular functions, including transcription regulation, signal transduction, DNA repair, and cell cycle processes. For the predicted binary protein complexes, they constructed spatial models, revealing that 1087 of these complexes had not been previously characterized in terms of their 3D structures. In addition, the top AF2 contact probability between residues of a protein pair can be used to distinguish true PPIs from false ones in yeast. Vasoactive intestinal peptide receptor 2 (VIPR2), a class B G-protein-coupled receptor, plays a role in numerous physiological processes through its interaction with vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP). VIPR2 has garnered interest as a potential therapeutic target in the fields of psychiatry, oncology, and immunology. In a study by Sakamoto, K., et al. [ 37 ], the researchers combined AF2 with molecular dynamics (MD) simulation techniques to construct models of the VIPR2/KS-133 and VIPR2/vasoactive intestinal peptide (VIP) complex and to understand their binding modes. The VIPR2/KS-133 and VIPR2/VIP complex models were constructed using AF2 and molecular dynamic simulations. 5.2. Biomarker Discovery Novel protein structure prediction algorithms provide information about the proteins’ structures that previously resisted attempts at experimental structure determination. A study published in Chemical Science applied AlphaFold to identify a new drug for hepatocellular carcinoma (HCC), the most common form of primary liver cancer [ 38 ]. This study used AlphaFold to predict the structure of CDK20 (Cyclin-Dependent Kinase 20), which is involved in cell cycle regulation; its abnormal activity can lead to uncontrolled cell growth, a hallmark of cancer. The researchers then identified potential inhibitor molecules using AI platforms developed by Insilico Medicine. They synthesized and tested these molecules, finding one, ISM042-2-048, with promising inhibitory activity against CDK20. 6. Comparative Analysis of Protein Structure Prediction Algorithms and Tools 6.1. Overview of the AlphaFold2 Algorithm AlphaFold2 (AF2) is a state-of-the-art computational framework specifically designed to predict the three-dimensional structures of proteins. It uses a combination of sequence and structural databases to gather the necessary information for its predictions. Sequence databases such as UniRef90, BFD, and the Mgnify microbiome database [ 39 ] provide access to amino acid sequences used to build a multiple sequence alignment (MSA) for the query sequence; AF2 then uses the experimental structures from the PDB [ 24 ] to train the “structural module” that builds the final model. MSA of the sequences of the query homologs is used to predict pairwise distances between residues (a distance map), which are later refined in several rounds of iterations reconciling initial distance predictions with the constraints of the subsequent models of the query. AF2’s architecture and training methodology contributed to its high accuracy in 3D protein structure prediction and allowed it to dramatically improve the quality of protein structure predictions. At the same time, its singular focus on structure prediction and extensive use of multiple MSAs may have limited its ability to predict changes to structure caused by small changes in sequence (single point mutations) and affected its accuracy in predictions for “orphans”, proteins with few or no known homologs ( Figure 3 ). Figure 3 Model Architecture of AlphaFold2. The architecture of the AlphaFold2 model can be broadly divided into three parts: (1) Model Input (2) Evoformer (3) Structure module. 6.2. Overview of the ESMFold Algorithm The ESMFold model [ 8 ] is built upon a BERT-like architecture, which is a type of large language model that utilizes stacked Transformer encoder layers. It is trained using a technique known as masked residue prediction, where certain amino acids in the protein sequence are hidden from the model during training, forcing it to predict these residues based on the surrounding context. This training process enables ESMFold to develop intricate internal representations of protein sequences. A notable feature of the ESM language model is its ability to infer structural information from protein sequences without relying on MSAs or known protein homologies. The model’s attention maps, derived from sequence embeddings, are used to predict the contact map. This capability is based solely on the amino acid sequence of the protein, making ESMFold a valuable tool for studying proteins that are difficult to analyze using traditional methods that depend on evolutionary comparisons ( Figure 4 ). Figure 4 Model Architecture of ESMFold. The ESMFold model can be divided into four parts: data parsing, encoder (Folding Trunk), decoder (Structure Module), and the recycling phase. 6.3. Overview of the RoseTTAFold Algorithm Developed by David Baker’s group at the Institute for Protein Design at the University of Washington, RoseTTAFold [ 7 ] is an extension of the older Rosetta family of tools, enhanced by the deep learning technology. It employs a unique ‘three-track’ neural network and integrates three types of information: the sequential patterns in proteins, the interplay between amino acids, and the probable three-dimensional configurations. RoseTTAFold has recently been updated to model complete biological assemblies, including a range of biomolecules such as proteins, DNA, and RNA. This enhancement broadens the potential uses of protein structure prediction algorithms [ 40 ]. 6.4. Overview of the OpenFold Algorithm The OpenFold Consortium introduced OpenFold, an open-source, trainable version of AF2, alongside OpenProteinSet, a database of 5 million diverse MSAs. This eliminates the massive computational barrier—millions of CPU hours—required for large-scale training. When trained from scratch using OpenProteinSet, OpenFold matches AF2’s prediction quality but offers advantages like faster processing, lower memory usage for handling longer proteins on a single GPU, and compatibility with the widely used PyTorch machine learning framework. This makes OpenFold easily accessible to a broad developer community [ 9 ]. Using OpenFold, researchers explored the model’s protein-folding learning process, identifying distinct behavioral phases during intermediate training stages. They discovered that OpenFold learns spatial dimensions and structural elements in an interleaved fashion. With OpenFold achieving 90% accuracy in just 3% of the training time as AF2, its retraining on pruned data sets showcased robustness and varied generalization capabilities. Training on smaller, diverse data sets further enhanced OpenFold’s performance. These findings provide valuable insights into AF2-type models and pave the way for advancements in biomolecular modeling algorithms. 6.5. Comparing AlphaFold2 vs. ESMFold vs. RoseTTAFold vs. OpenFold In protein structure prediction, utilizing individual sequences without relying on co-evolutionary data like MSA emerges as a promising strategy. This method potentially eliminates the time needed for homology searches and MSA building and may enhance prediction accuracy for orphan proteins. Although explored in earlier research by Chowdhury et al. and Wang et al. [ 41 , 42 ], the results were initially less than ideal. However, recent ESMFold results indicate that larger pre-trained models alongside techniques inspired by AF2’s distillation method can enhance prediction accuracies. This improvement is attributed to two primary factors. First, the size of the sequence pre-trained models has been significantly increased, with ESMFold now using a 15B model that encapsulates more co-evolutionary information. Second, instead of employing self-distillation, a technique known as AF2 distillation has been adopted. In this approach, AF2 is utilized to perform structure predictions on a large sequence database, and the predicted structures are then used as training data for ESMFold. This innovative method of utilizing AlphaFold2’s predictive power to enrich the training data has contributed to the enhanced performance of ESMFold in protein structure prediction. For instance, ESMFold, with fewer parameters, predicts a protein with 384 residues in just 14.2 s on a single NVIDIA V100 GPU, about 6 times faster than AF2. The strategies employed by AF2, ESMFold, RoseTTAFold and OpenFold in protein structure prediction offer distinct advantages and limitations. ESMFold’s approach of using individual sequences for predictions is time-efficient and particularly beneficial for orphan proteins, which lack homologs in current databases. ESMFold, demonstrates a significant speed advantage over AF2, enabling the rapid construction of predicted structures, a crucial factor given the vast amount of available sequence data. On the other hand, AF2’s methodology, as summarized in the overview, leverages MSA and structural databases to interpret coevolutionary correlations between mutations for its predictions. However, this approach may pose challenges in handling novel single-point mutations or orphan proteins and concerns regarding data leakage in evaluation data sets. RoseTTAFold can predict protein–nucleic acid complexes, though its precision in this area is not as high as when dealing with protein structures alone. To enhance this capability, the RoseTTAFoldNA extension has been developed, specifically focusing on improving the predictions of protein-nucleic acid complexes [ 43 ]. The contrasting approaches among AF2, ESMFold, RoseTTAFold and OpenFold highlight the trade-offs between prediction speed and accuracy and need for additional input data ( Table 2 ). We compared the algorithms used by AF2, ESM2 and OpenFold focusing on the input and frameworks in Supplementary Table S1 . Table 2 Capabilities of and differences between these four protein structure prediction models. Model Speed Accuracy [ 44 ] Use of MSA Strength AlphaFold2 Requires high-powered and high-capacity computing resources AlphaFold2 attains a mean GDT-TS score of 73.06. Yes, leverages MSA for rich evolutionary context High accuracy ESMFold 6× faster than a single AlphaFold2 model. ESMFold attains a mean GDT-TS score of 61.62. No, predicts structures from a single sequence Fast prediction speed RoseTTAFold Vary depending on the specific protein and computational resources, compared to AlphaFold2. In over 80% of cases, RoseTTAFold’s performance was lower than ESMFold, with the latter achieving a higher mean GDT-TS score. Yes, uses MSAs predicting protein complexes with RNA or DNA OpenFold Slightly faster than AlphaFold2 [ 45 ].

Yes, uses MSAs Allows for application-specific training 6.6. AI Tools in Protein Sequence Generation and Structure Design Generating protein sequences for novel proteins with designed structures and functions is an interesting extension of the protein structure prediction problem, pave the way for novel treatment options. Computational models like ProGen, ProteinMPNN, EvoDiff, and RFDiffusion are being leveraged to accelerate this process. ProGen, short for Protein Generator, is a protein language model developed by Salesforce AI Research that generates protein sequences with predictable functions [ 10 ]. ProGen, a 12-billion-parameter neural network, generates protein sequences for specific biological functions. It uses functional tags from the Pfam database and is trained on 280 million protein sequences. Researchers have fine-tuned it with distinct enzyme families, resulting in millions of sequences that closely resemble natural enzymes. ProteinMPNN [ 11 ] is a deep learning algorithm designed for protein sequence design. It extends the message-passing neural network (MPNN) framework, which is a machine learning technique that can predict the properties of properties by simulating how residues send and receive information to and from their neighbors. ProteinMPNN has been extended to design protein–nucleic acids and protein–small molecules, which will greatly increase its utility. EvoDiff, a general-purpose diffusion framework developed by Microsoft [ 12 ], is tailored for generating protein sequences and evolutionary alignments. It capitalizes on large-scale evolutionary data and the unique conditioning strengths of diffusion models. A prominent attribute of EvoDiff is its ability to generate proteins based solely on their sequence information. This streamlines the protein design process, as it negates the necessity for comprehensive structural data. RFDiffusion, used in protein engineering, leverages generative AI to generate novel protein sequences and structures. RFDiffusion is a generative model that creates protein sequences and structures using denoising diffusion probabilistic models [ 13 ]. RFDiffusion takes a unique approach by adding Gaussian noise independently to the rotation and translation matrices of the protein’s 3D coordinates to generate training data. This results in a model with higher-dimensional representation capabilities and global rotational invariance, which in turn enables more stable model training. During the denoising process, each step of the model predicts the structure after local denoising for the subsequent step. This predicted structure then serves as the initial coordinate and structural template for further predictions. Ablation studies have confirmed the importance of these templates in generating high-quality protein structures. Additionally, RFDiffusion incorporates a sequence information channel. Sequences that are masked during the diffusion process gradually recover, mirroring a training task approach from a previous model, RFjoint [ 46 ]. This allows RFDiffusion to predict amino acid distributions at masked string positions, and it has led to speculation that RFDiffusion might essentially be an evolved version of RFjoint, enhanced by adding structural template noise. Moreover, RFDiffusion offers different versions tailored to specific tasks, such as fixing known or functional segment structures, broadening its applicability in protein research ( Figure 5 ). Figure 5 Model structure of RFDiffusion. Use of the diffusion model approach for training and fine-tuning the protein structure prediction model, enabling a more refined depiction of the hidden relationship between protein sequences and structures. 6.7. AI Tools in Docking Used in Drug Discovery Docking, a computational strategy, predicts how two molecules form a stable complex and is usually separated into ligand docking and protein–protein docking. AI boosts this process’s speed and precision. Deep Docking (DD), an AI enabled methodology for virtual screening of ultra-large chemical libraries, significantly accelerates structure-based virtual screening. DD iteratively docks subsets of a chemical library, synchronized with ligand-based predictions, to enhance virtual hit enrichment without substantial loss of potential drug candidates [ 47 ]. DiffDock, an AI-driven tool from MIT, frames molecular docking as a generative modeling problem. It maps the manifold of ligand poses to the product space of the degrees of freedom involved in docking (translational, rotational, and torsional) and develops an efficient diffusion process on this space [ 14 ]. 7. Generative AI: A Catalyst in Cancer Drug Development Generative AI has emerged as a transformative force in the life sciences sector ( Figure 6 ), powering innovative research, optimizing workflows, and providing new insights. Its applications are extensive and varied: We previously discussed de novo design of proteins [ 48 , 49 ], the creation of novel antibodies [ 50 ], and the building of comprehensive models for single-cell multi-omics [ 51 ], which can provide a deeper understanding of the cellular heterogeneity in tumors and inform the development of personalized cancer treatments. Figure 6 Generative AI in Life Sciences: A Comprehensive Overview of Applications and Innovations. Generative AI is revolutionizing various aspects of life sciences. It is accelerating drug discovery, aiding in antibody development, and enhancing single-cell multi-omics models for disease understanding. The technology also plays a role in personalized medicine, population genetics, and viral evolution. Beyond biology, it is pivotal in data science for generating synthetic data and in scientific visualization through text-to-image technologies. Overall, generative AI’s impact is expansive and transformative across life sciences. Moreover, generative AI also plays a role in genomic variant effect prediction [ 52 ] and identifying statistical patterns in DNA sequences [ 53 ], which can help in understanding the genetic basis of cancer. It is instrumental in predicting and reconstructing the evolution of viruses [ 54 ], thus offering valuable insights for epidemiology and vaccine development. Additionally, this technology can generate synthetic data to augment existing data sets [ 55 ], providing a valuable resource for researchers and scientists. Even in the realm of data visualization, generative AI can be used for text-to-image generation [ 56 , 57 ], translating complex textual descriptions into accurate, understandable biological images. Overall, by enabling a deeper understanding of biological systems and accelerating the discovery process, it holds great promise in advancing the fight against cancer. 8. Beyond Cancer: AI Driven Drug Discovery for Other Diseases Researchers at MIT used AI to discover a new antibiotic, named “halicin”, effective against E. coli and drug-resistant Acinetobacter baumannii. They trained a neural network on a data set of 2335 molecules that inhibit E. coli and refined the model with feature engineering and other techniques. The AI model analyzed over 107 million molecules to identify potential antibiotics against E. coli. Using the model’s predictions, a shortlist of the most promising candidates was created and empirically tested for their antibacterial properties [ 58 ]. In early 2020, Exscientia reported the initiation of Phase 1 clinical trials for DSP-1181, a compound designed to address obsessive-compulsive disorder. Developed through AI, the compound was identified by screening chemical libraries for the most pertinent candidates. DSP-1181 is reported to be the first drug of its kind to reach the clinical trial stage [ 59 ]. It was the first AI-designed drug candidate to enter clinical trials, which was a pivotal moment in AI drug discovery. In February 2023, Insilico Medicine received the FDA’s first-ever Orphan Drug Designation for a medication discovered and developed through AI technology. The drug, named INS018_055, is designed as a small molecule inhibitor for treating idiopathic pulmonary fibrosis (IPF). Utilizing their proprietary Pharma.AI platform, Insilico not only identified a new target but also generated innovative small molecules. Following the successful completion of Phase 0 and Phase I safety studies, the drug has now advanced to multi-regional Phase II clinical trials in the United States and China [ 60 , 61 ]. AI has been employed in the quest for COVID-19 therapeutics. Researchers combined AI with fragment-based drug design to speed up the identification of potential drugs against SARS-CoV-2. Using a molecular library of known SARS-3CLpro inhibitors; they utilized AI to generate new compounds targeting the virus’s essential 3CL protease. These AI-generated molecules were then screened for their ability to inhibit viral replication by binding covalently to the 3CL protease [ 46 ]. In a different study, deep neural networks were used to create new small molecules targeting SARS-CoV-2’s 3CL protease. Utilizing transfer and reinforcement learning, the generative model was fine-tuned to focus on known protease inhibitors. The training data came from the ChEMBL database of viral protease inhibitors [ 62 ]. 9. Limitations and Challenges AF2 demonstrates high accuracy in predicting the three-dimensional structures of proteins, particularly when sequences of multiple homologs are available in sequence databases to construct an MSA. However, along with other AI tools, it requires substantial computational resources. This can limit its accessibility for researchers with limited computational capabilities [ 63 ]. The integration of AI into the drug discovery process also presents regulatory and implementation challenges. These include ensuring data privacy and security, validating the effectiveness of AI-based predictions, and adapting existing workflows and systems to incorporate AI tools [ 64 ]. The challenge of ligand-induced folding, especially in regions of proteins that are intrinsically disordered or “floppy”, has been a significant obstacle in drug discovery and development [ 35 ]. AF2, despite its groundbreaking contributions to protein structure prediction, primarily predicts a single static state of a protein. This approach overlooks the dynamic conformational changes critical for enzyme function and drug interaction, such as adjustments at the binding site or domain shifts. These dynamic changes are essential for understanding how a protein functions in its natural environment and how it interacts with potential drug molecules [ 35 ]. The study by Fernández [ 65 ] introduced a deep learning approach to address the challenge of binding-induced folding in a protein’s intrinsically disordered regions. However, the conformational change induced by drug folding in proteins with multiple domains or involved in protein–protein interactions remains a challenge [ 66 ]. Finally, it is important to note that in drug discovery, understanding a protein’s structure, while insightful, is seldom the primary bottleneck; the process is driven more by empirical data from assays, pharmacokinetics, metabolism, and toxicology, emphasizing that the success of drug discovery hinges on multiple factors. As the field of protein structure prediction continues to evolve, it is expected that further advancements will be made in the accuracy and applicability of AI tools. These improvements may include enhanced performance on challenging protein classes and complexes, better handling of protein dynamics and conformational changes, and reduced reliance on homologous templates for accurate predictions [ 35 ]. Additionally, incorporating experimental constraints and other sources of information into the modeling process may help to increase the accuracy and reliability of structure predictions for a wider range of protein targets. 10. Conclusions AI is poised to significantly transform the landscape of drug development, offering ways to streamline the process, reduce costs, and enhance success rates at various stages. The process started with AF2, which has achieved remarkable success in predicting protein structures, marking a milestone for AI applications in structural biology. By providing accurate predictions of protein structures, AF2 can accelerate the development of new cancer drugs and therapies, and more effectively identify and validate novel drug targets, particularly for those lacking substantial structural information. Perhaps more importantly, AF2 has inspired a wave of AI-driven tools in protein structure prediction, engineering, docking, and generating novel proteins with desired structures and functions. These tools exemplify the role of AI in advancing drug development by enabling the generation of novel protein sequences and structures, predicting the effects of genomic variants, and providing new insights into the mechanisms of cancer. Acknowledgments We acknowledge ChatGPT ( https://chat.openai.com/ ) and Grammarly ( https://app.grammarly.com/ ) for their assistance in proofreading the initial draft of our manuscript. We used these tools solely to improve grammar and style of the writing. We also acknowledge Midjourney ( https://www.midjourney.com/ ) for the generation of some of the icons used in the graphical abstract. Finally, we would like to acknowledge BioRender ( https://www.biorender.com/ ) for providing the platform to create the figures used in this manuscript. Supplementary Materials The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/biom14030339/s1 , Table S1. Comparison of algorithms among AF2, ESM2 and OpenFold. Author Contributions Conceptualization, X.Q. and A.G.; validation, X.Q., H.L., G.V.S. and A.G.; investigation, X.Q., H.L., G.V.S. and A.G.; writing—original draft preparation, X.Q., H.L., G.V.S. and A.G.; writing—review and editing, X.Q., H.L., G.V.S. and A.G.; visualization, X.Q. and H.L.; supervision, A.G.; project administration, A.G.; funding acquisition, A.G. All authors have read and agreed to the published version of the manuscript. Conflicts of Interest The authors declare no conflict of interest. Funding Statement Work on this review was partly funded by NIAID contract #75N93022C00035. Footnotes Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. References 1. 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2397 biomol Biomolecules Biomolecules 多学科数字出版研究所 (MDPI) PMC10968151 10968151 10968151 38540759 10.3390/biom14030339 人工智能在蛋白质结构预测中的进展:对癌症药物研发的影响 邱新茹 1 李涵 2 Ver Steeg Greg 2 Godzik Adam 1 * Paiardini Alessandro 学术编辑 1 加州大学河滨分校医学院生物医学科学系,美国加利福尼亚州河滨市 92521;xinru.qiu@ucr.edu 2 加州大学河滨分校计算机科学与工程系,美国加利福尼亚州河滨市 92521;han.li001@email.ucr.edu (H.L.);greg.versteeg@ucr.edu (G.V.S.) * 通讯作者:adam.godzik@medsch.ucr.edu 2024年3月12日 14 3 339 339 2024年3月28日 © 2024 作者所有。由瑞士巴塞尔MDPI授权发布。本文采用知识共享署名4.0国际许可协议(CC BY)进行开放获取分发(https://creativecommons.org/licenses/by/4.0/)。 摘要 人工智能(AI)驱动技术的最新进展,特别是在蛋白质结构预测领域,正在显著重塑药物研发格局。本综述聚焦于以AlphaFold2为代表的技术突破如何革新我们对癌症相关蛋白质结构与功能变化的理解,并改进我们应对这些变化的方法。通过提高靶点识别的精度以及药物候选分子设计与优化的速度,这些技术正在简化整个药物研发流程。我们探讨了AlphaFold2在癌症药物开发中的应用,审视其有效性、局限性及潜在挑战。同时,我们将AlphaFold2与ESMFold等其他算法进行比较,阐述该领域所采用的不同方法学及其差异对特定算法实际应用的影响。此外,我们还讨论了这些技术的更广泛应用,包括蛋白质复合物结构的预测以及基于生成式AI的新型蛋白质设计。 关键词:AlphaFold2,癌症,药物发现,人工智能,生成式AI 状态 已发布 display-pdf 是 is-olf 否 is-manuscript 否 is-preprint 否 is-journal-matter 否 is-scanned 否 is-retracted 否 收稿日期:2024年1月30日;修订日期:2024年3月4日;接受日期:2024年3月6日;收录日期:2024年3月。 1. 引言 由人工智能(AI)技术近期革命性进展驱动的ChatGPT、DALL-E等工具,因其不断扩展的能力及其给社会带来的承诺与潜在威胁而受到广泛关注。然而,AI驱动的科学领域突破早已在进行之中。本综述深入探讨了由2021年AlphaFold2(AF2)深度神经网络算法引入所催生的结构生物学领域的深刻变革,以及随后出现的其他算法。这些工具共同有效解决了结构生物学中长期存在的挑战:仅从序列信息生成蛋白质结构的原子级模型[1,2,3]。本综述旨在探讨蛋白质结构预测领域的这些突破如何影响药物发现过程,初步聚焦于癌症研究,并讨论特定算法的架构和假设如何影响和区分其结果。 药物发现过程常常以低效为特征,表现为成本上升、时间延长和高失败率。只有一小部分药物候选分子能进入临床试验,且许多在III期才失败,导致临床药物开发的总体成功率约为10–20%[4]。据估计,在产品上市前的总体研发费用范围从每成功一种药物1.61亿美元到45.4亿美元(按2019年美元计)[5](图1)。这种低效部分归因于我们对人类生物学,特别是疾病过程的理解不足;缺乏可操作的治疗靶点;以及对不同人群疾病反应多样性的理解有限[6]。使这一过程更加复杂的是,缺乏准确代表疾病的临床前模型以及过于简化的疾病模型限制,这些都增加了理解人类系统复杂性的难度。缺乏高质量的药物靶点结构模型是AlphaFold要解决的主要问题之一,但这只是药物发现中的挑战之一。然而,正如我们在本综述中所展示的,AI在解决药物开发的其他瓶颈方面也取得了快速进展。 图1 药物发现过程的阶段:药物发现过程包含几个关键阶段。它始于“发现与开发”阶段,重点是靶点识别与验证。该阶段涉及筛选潜在化合物,并通过苗头到先导(hit-to-lead)开发和先导优化进一步精炼有前景的候选分子。随后,过程进入“临床前开发”,包括一系列实验室测试,如体外研究、动物模型测试和ADMET(吸收、分布、代谢、排泄、毒性)研究。基于这些结果,决定是否进入下一阶段。“临床试验”随之开始,分为四个阶段:I期评估安全性和剂量;II期检验疗效和副作用;III期涉及更大规模研究以确认疗效和监测不良反应;最后阶段是“审查与批准”,包括全面的监管审查,最终获得上市许可,随后进行上市后监测以确保长期安全性和有效性,构成新定义的IV期。 传统上,蛋白质的三维结构是通过劳动密集型且昂贵的实验方法解析的,如X射线晶体学、核磁共振(NMR)和冷冻电子显微镜(cryo-EM)。尽管这些技术非常有用,但受限于速度、成本以及仅适用于某些蛋白质结构。相比之下,蛋白质结构预测的最新进展,以AF2为顶峰,极大地扩展了我们的能力,补充并有时超越了实验方法。AF2的突破很快被其他AI工具跟进,如RoseTTAfold[7]、ESMFold[8]和OpenFold[9]。ProGen[10]、ProteinMPNN[11]、EvoDiff[12]和RFdiffusion[13]将AI能力扩展到新型蛋白质设计,DiffDock[14]则扩展到分子对接。这些以及许多其他快速发展的工具应用了新颖的算法和AI架构,各有独特的优势和劣势。在这里,我们不太关注它们预测结果的比较,而更关注其算法和方法的差异以及由此产生的最佳应用场景。 2. AlphaFold之前的蛋白质计算机模拟结构预测 在AlphaFold出现之前的时期,蛋白质结构预测过程通常包含几个不同的阶段,如下文所述(图2)。 图2 蛋白质结构预测的阶段:基础阶段涉及确定编码目标蛋白的DNA序列。下一步是从DNA序列推断蛋白质序列。同源建模使用已知蛋白质结构作为模板来预测具有未知结构但序列相似的蛋白质的结构。最后,结构验证确保预测结构的生物学合理性。这涉及检查立体化学质量、能量评估以及与已知结构数据的比较。 2.1. 同源与比较建模 同源建模利用同源蛋白质的结构来预测蛋白质的3D结构。它包括四个步骤:识别具有已知结构的同源蛋白质(靶点识别)、将靶标与模板序列比对(比对)、从比对区域构建靶蛋白模型(模型构建)以及提高模型的准确性和稳定性(模型优化)。远缘同源识别和远缘同源之间比对的改进以HHpred算法及配套程序套件为例[15,16]。从共进化模式预测蛋白质接触图从另一个角度解决了这个问题[17],并因深度学习神经网络的首次应用而得到增强[18]。在2010年代末,Rosetta[19]和I-Tasser[20]等工具跨越了从同源建模到比较建模的界限[21]。Rosetta通过使用已知结构的较小单元以及类能评分函数和实验折叠规则的组合实现了这一点。I-TASSER(迭代线程组装细化)的相似性使用了基于模板的建模和片段组装的组合。其他工具的相似性已开始接近从头(ab-initio)蛋白质结构预测的水平[21]。这些进展直接导致了AlphaFold的开发以及随后AI在蛋白质结构预测中的应用。 2.2. 结构验证 结构验证确保预测的准确性和合理性。如[22]等工具分析结构特征的几何形状并验证拉氏图中的二面角。基于能量的评估,如ANOLEA[23],评估势能以评估折叠的正确性。最后,如果有的话,可以将预测结构与实验数据进行比较。这种比较可用于基准测试预测方法并建立预期准确性,但不能用于评估没有已知实验结构的蛋白质的预测。然而,基于预测的3D结构的功能预测,如活性位点或相互作用界面残基的鉴定,可以在体外进行测试,从而间接确认结构预测。 3. 现有蛋白质结构数据集及其应用 现有蛋白质结构数据集在蛋白质生物信息学中起着关键作用(表1)。由各个结构生物学研究组通过实验方法解析的蛋白质结构被提交给结构生物信息学研究合作实验室(RCSB)蛋白质数据库(PDB)[24]。基于AI的结构预测的实际应用因AlphaFold蛋白质结构数据库的开发而变得更加容易,该数据库提供了超过2亿个蛋白质结构的预计算预测。AlphaFold2和UniProt数据库的整合将蛋白质结构信息的访问范围扩展到了广大生物学家群体[25,26]。ESM宏基因组图谱包含来自土壤、海水和人体肠道等环境中发现的超过7亿个各种微生物的蛋白质结构预测。这一全面的预测结构集合为宏基因组景观提供了宝贵的见解[8]。这些数据集共同支持广泛的研究和应用,包括开发和评估机器学习模型、推进我们对蛋白质生物学的理解以及促进药物发现工作。 表1 公开可用的蛋白质结构数据集及其在药物发现不同阶段的应用。 资源 用途 数据仓库及参考文献 蛋白质数据库(PDB) 提供蛋白质、核酸和复杂组装体的3D结构,可用于药物靶点识别、配体设计和理解蛋白质-配体相互作用。 RCSB PDB [27] AlphaFold蛋白质结构数据库 包含几种生物体整个蛋白质组的蛋白质结构预测。可用于靶点识别和理解蛋白质功能。 AlphaFold DB [25,26] CASP(蛋白质结构预测关键评估) 托管来自CASP竞赛的蛋白质结构预测模型,可用于评估和改进结构预测方法。 CASP [28] SWISS-MODEL存储库 由SWISS-MODEL同源建模流程生成的带注释的3D蛋白质结构模型数据库,可用于结构预测和药物设计。 SWISS-MODEL [29] ESM宏基因组图谱 ESM宏基因组图谱展示了来自土壤、海水和人体肠道等环境中微生物的超过7亿个预测蛋白质结构,可通过交互式页面访问。 ESM Atlas [8] 4. 疾病理解——基于AI的结构预测应用实例 理解致病突变 AF2蛋白质结构预测有助于识别遗传性癌症基因中的致病错义变异。在Karakoyun等人[30]的一项研究中,使用AF2预测的结构和五种蛋白质稳定性预测因子来评估来自ClinVar和乳腺癌患者队列的一千多个错义变异的致病性。他们的发现表明,蛋白质稳定性预测因子在识别致病变异方面表现出中等效果。然而,AF2置信度评分pLDDT在预测致病性方面表现出更优的能力,突出了AF2在识别与癌症相关的遗传变异方面的潜力。 AF2还可以帮助我们理解疾病蛋白质旁系同源物的作用。例如,人类二酰甘油激酶(DGK)功能障碍与多种疾病相关,包括癌症和自身免疫性疾病。然而,由于缺乏所有10种人类DGK旁系同源物的高分辨率结构,DGK功能障碍如何促进这些疾病发展的确切机制尚不完全清楚。在最近的一项研究[31]中,研究人员使用AF2预测了所有人类DGK旁系同源物的三维结构,并对预测进行了结构比对,以揭示保守结构域及其相对于彼此的空间排列。该研究还使用对接研究来证实催化和辅助结构域之间保守ATP结合位点的存在,并研究DGK相对于膜的空间排列。 AF2可以通过准确预测蛋白质3D结构并识别潜在变构结合位点来辅助药物发现。变构药物结合变构位点而非活性位点,可以诱导蛋白质的构象变化,影响其活性。这使得能够设计更有效的药物,与传统正位药物协同作用以提高疗效。Nussinov, R.等人[32]的一项研究说明了变构药物如何改变耐药突变产生的活性位点构象,允许被阻断的正位药物结合。这表明变构和正位药物的组合可能比任何一种药物类型单独使用更有效。在Weng, Y.等人[33]的另一项研究中,使用AF2预测了WSB1的蛋白质结构。然后使用分子动力学模拟优化预测结构,并使用软件进行验证。之后,使用AutoDock-GPU和Glide进行虚拟筛选,使用基于配体或基于结构的方法过滤化合物。最后,选择了四种具有不同化合物支架的化合物作为WSB1的潜在抑制剂。 在最近的发展中,由Google DeepMind设计的计算工具AlphaMissense被证明能够正确评估错义变异的致病潜力[34]。通过利用AlphaFold的结构见解,AlphaMissense评估突变对蛋白质功能的影响。在癌症药物发现领域,该工具在帮助研究人员高效选择基因突变进行深入研究方面具有巨大潜力。这可以加速识别新型药物靶点的过程。此外,AlphaMissense有可能增强我们对遗传密码中较少探索部分的理解,特别是那些在人类健康中起关键作用但其功能尚未完全了解的基因。 5. 靶点识别 理解疾病分子机制后的下一步是识别治疗干预的靶点。同样,了解在癌症中发生突变或修饰的通路或网络中涉及的蛋白质结构,是识别最佳药物靶点的重要步骤。在分子水平上理解疾病的分子机制,包括基因产物改变的功能、相互作用和机制含义,对于开发癌症的靶向治疗策略至关重要。通过对这些方面进行建模,研究人员可以评估和比较纠正基因突变引起的不良结果的不同策略。此类分子模型在设计有效癌症疗法中起着重要作用[35]。 5.1. 蛋白质复合物结构的预测 准确预测蛋白质复合物结构对癌症药物发现至关重要,为信号转导的分子机制(其中信号通路上游和下游元件之间的物理相互作用用于传递信号)或间接突变影响(当复合物中另一个元件的突变改变关键蛋白质的功能)提供了见解。基于结构的方法在开发特异性和有效药物以及解决耐药性问题方面发挥着重要作用。它们还通过识别特定患者癌细胞中的独特脆弱性来支持个性化治疗,并有助于最小化药物副作用和相互作用。在Zhang, J.等人[36]的一项研究中,AF2被用于预测参与癌症蛋白质-蛋白质相互作用(PPIs)的蛋白质复合物结构。研究人员利用AF2探索与癌症相关的蛋白质-蛋白质相互作用组,识别了1798种与癌症驱动蛋白相关的潜在蛋白质-蛋白质相互作用(PPIs)。这些蛋白质在多种细胞功能中发挥作用,包括转录调控、信号转导、DNA修复和细胞周期过程。对于预测的二元蛋白质复合物,他们构建了空间模型,揭示其中1087种复合物的3D结构尚未被表征。此外,蛋白质对之间残基的AF2最高接触概率可用于区分酵母中的真实PPI与假PPI。 血管活性肠肽受体2(VIPR2)是一种B类G蛋白偶联受体,通过与血管活性肠肽(VIP)和垂体腺苷酸环化酶激活多肽(PACAP)的相互作用参与多种生理过程。VIPR2作为精神病学、肿瘤学和免疫学领域的潜在治疗靶点引起了兴趣。在Sakamoto, K.等人[37]的一项研究中,研究人员将AF2与分子动力学(MD)模拟技术相结合,构建了VIPR2/KS-133和VIPR2/血管活性肠肽(VIP)复合物的模型并理解其结合模式。VIPR2/KS-133和VIPR2/VIP复合物模型是使用AF2和分子动力学模拟构建的。 5.2. 生物标志物发现 新型蛋白质结构预测算法提供了以前难以通过实验方法解析的蛋白质结构信息。发表在《Chemical Science》上的一项研究应用AlphaFold识别了一种用于治疗肝细胞癌(HCC,最常见的原发性肝癌形式)的新药[38]。该研究使用AF2预测了CDK20(细胞周期蛋白依赖性激酶20)的结构,CDK20参与细胞周期调节;其异常活动可导致不受控制的细胞生长,这是癌症的一个标志。然后,研究人员使用Insilico Medicine开发的AI平台鉴定了潜在的抑制剂分子。他们合成并测试了这些分子,发现一种名为ISM042-2-048的分子对CDK20具有有前景的抑制活性。 6. 蛋白质结构预测算法与工具的比较分析 6.1. AlphaFold2算法概述 AlphaFold2(AF2)是一个最先进的计算框架,专门设计用于预测蛋白质的三维结构。它结合使用序列和结构数据库来收集预测所需的信息。UniRef90、BFD和Mgnify微生物组数据库[39]等序列数据库提供用于构建查询序列多序列比对(MSA)的氨基酸序列;AF2随后使用PDB[24]中的实验结构来训练构建最终模型的“结构模块”。查询同源序列的MSA用于预测残基之间的成对距离(距离图),该距离图在几轮迭代中随后与后续查询模型的约束相协调,从而得到改进。AF2的架构和训练方法有助于其在3D蛋白质结构预测中的高精度,并显著提高了蛋白质结构预测的质量。同时,其对结构预测的单一关注和对多个MSA的广泛使用可能限制了其预测由序列微小变化(单点突变)引起的结构变化的能力,并影响了其对“孤儿蛋白”(具有很少或没有已知同源物的蛋白质)预测的准确性(图3)。 图3 AlphaFold2的模型架构。AlphaFold2模型的架构大致可分为三部分:(1) 模型输入 (2) Evoformer (3) 结构模块。 6.2. ESMFold算法概述 ESMFold模型[8]基于BERT类架构,这是一种利用堆叠Transformer编码器层的大型语言模型。它使用一种称为掩蔽残基预测的技术进行训练,其中蛋白质序列中的某些氨基酸在训练过程中被隐藏,迫使模型根据周围上下文预测这些残基。这一训练过程使ESMFold能够发展出蛋白质序列的复杂内部表示。ESM语言模型的一个显著特征是能够从蛋白质序列推断结构信息,而无需依赖MSA或已知蛋白质同源性。从序列嵌入派生的模型的注意力图用于预测接触图。此能力仅基于蛋白质的氨基酸序列,使ESMFold成为研究难以使用依赖进化比较的传统方法进行分析的蛋白质的宝贵工具(图4)。 图4 ESMFold的模型架构。ESMFold模型可分为四个部分:数据解析、编码器(Folding Trunk)、解码器(结构模块)和回收阶段。 6.3. RoseTTAFold算法概述 由华盛顿大学蛋白质设计研究所David Baker团队开发的RoseTTAFold[7]是旧有Rosetta工具家族的扩展,并通过深度学习技术得到增强。它采用独特的“三轨”神经网络,整合了三种类型的信息:蛋白质中的序列模式、氨基酸之间的相互作用以及可能的三维构型。RoseTTAFold最近已更新为可建模完整的生物组装体,包括蛋白质、DNA和RNA等一系列生物分子。这一增强拓宽了蛋白质结构预测算法的潜在用途[40]。 6.4. OpenFold算法概述 OpenFold联盟推出了OpenFold,这是一个AF2的开源、可训练版本,以及OpenProteinSet,一个包含500万个多样化MSA的数据库。这消除了大规模训练所需的巨大计算障碍——数百万CPU小时。当使用OpenProteinSet从头训练时,OpenFold的预测质量与AF2相当,但具有更快的处理速度、在单个GPU上处理更长蛋白质的更低内存使用量以及与广泛使用的PyTorch机器学习框架兼容等优势。这使得OpenFold易于被广大开发者社区使用[9]。 使用OpenFold,研究人员探索了模型的蛋白质折叠学习过程,识别了中间训练阶段的不同行为阶段。他们发现OpenFold以交错的方式学习空间维度和结构元素。OpenFold仅用AF2训练时间的3%就达到了90%的准确性,其在精简数据集上的再训练展示了鲁棒性和不同的泛化能力。在更小、更多样化的数据集上训练进一步提高了OpenFold的性能。这些发现为AF2类模型提供了有价值的见解,并为生物分子建模算法的进步铺平了道路。 6.5. AlphaFold2 vs. ESMFold vs. RoseTTAFold vs. OpenFold 比较 在蛋白质结构预测中,利用单个序列而不依赖MSA等共进化数据成为一种有前景的策略。这种方法有可能消除同源搜索和MSA构建所需的时间,并可能提高孤儿蛋白的预测准确性。尽管在Chowdhury等人和Wang等人[41,42]的早期研究中已探索过,但结果最初并不理想。然而,最近的ESMFold结果表明,更大的预训练模型以及受AF2蒸馏方法启发的技术可以提高预测准确性。这种改进归因于两个主要因素。首先,序列预训练模型的规模显著增加,ESMFold现在使用包含更多共进化信息的15B模型。其次,没有采用自蒸馏,而是采用了一种称为AF2蒸馏的技术。在这种方法中,AF2被用于对大型序列数据库进行结构预测,然后预测的结构被用作ESMFold的训练数据。这种利用AlphaFold2预测能力来丰富训练数据的创新方法,有助于提高ESMFold在蛋白质结构预测中的性能。例如,参数更少的ESMFold在单个NVIDIA V100 GPU上仅用14.2秒就能预测一个含有384个残基的蛋白质,比AF2快约6倍。 AF2、ESMFold、RoseTTAFold和OpenFold在蛋白质结构预测中采用的策略各有优势和局限。ESMFold使用单个序列进行预测的方法省时,特别有利于在当前数据库中缺乏同源物的孤儿蛋白。ESMFold相比AF2表现出显著的速度优势,能够快速构建预测结构,鉴于可用序列数据量巨大,这是一个关键因素。另一方面,AF2的方法,如概述中总结,利用MSA和结构数据库来解释其预测中突变之间的共进化相关性。然而,这种方法在处理新型单点突变或孤儿蛋白时可能面临挑战,并存在评估数据集中数据泄露的担忧。RoseTTAFold可以预测蛋白质-核酸复合物,但其在这方面的精度不如单独处理蛋白质结构时高。为了增强这一能力,已开发了RoseTTAFoldNA扩展,专门用于改进蛋白质-核酸复合物的预测[43]。 AF2、ESMFold、RoseTTAFold和OpenFold之间的对比方法突出了预测速度与准确性之间的权衡以及对额外输入数据的需求(表2)。我们比较了AF2、ESM2和OpenFold使用的算法,重点关注输入和框架,见补充表S1。 表2 这四种蛋白质结构预测模型的能力和差异。 模型 速度 准确性[44] 使用MSA 优势 AlphaFold2 需要高功率和大容量计算资源 AlphaFold2达到73.06的平均GDT-TS分数。 是,利用MSA获得丰富的进化背景 高准确性 ESMFold 比单个AlphaFold2模型快6倍。 ESMFold达到61.62的平均GDT-TS分数。 否,从单个序列预测结构 预测速度快 RoseTTAFold 根据特定蛋白质和计算资源而变化,与AlphaFold2相比。 在超过80%的情况下,RoseTTAFold的性能低于ESMFold,后者实现了更高的平均GDT-TS分数。 是,使用MSA 预测与RNA或DNA的蛋白质复合物 OpenFold 比AlphaFold2略快[45]。 是,使用MSA 允许特定应用的训练 6.6. 蛋白质序列生成与结构设计中的AI工具 为具有设计结构和功能的新型蛋白质生成序列是蛋白质结构预测问题的一个有趣扩展,为新的治疗选择铺平了道路。ProGen、ProteinMPNN、EvoDiff和RFDiffusion等计算模型正被用于加速这一过程。 ProGen(蛋白质生成器)是由Salesforce AI Research开发的一种蛋白质语言模型,可生成具有可预测功能的蛋白质序列[10]。ProGen是一个120亿参数的神经网络,为特定生物功能生成蛋白质序列。它使用Pfam数据库中的功能标签,并在2.8亿个蛋白质序列上进行训练。研究人员用不同的酶家族对其微调,产生了数百万个与天然酶非常相似的序列。 ProteinMPNN[11]是一种为蛋白质序列设计而设计的深度学习算法。它扩展了消息传递神经网络(MPNN)框架,这是一种可以通过模拟残基如何向邻居发送和接收信息来预测性质的机器学习技术。ProteinMPNN已被扩展用于设计蛋白质-核酸和蛋白质-小分子,这将大大增加其效用。 EvoDiff是由微软开发的一种通用扩散框架[12],专为生成蛋白质序列和进化比对而定制。它利用大规模进化数据和扩散模型独特的调节能力。EvoDiff的一个突出属性是能够仅基于其序列信息生成蛋白质。这简化了蛋白质设计过程,因为它否定了对全面结构数据的必要性。 RFDiffusion用于蛋白质工程中,利用生成式AI生成新型蛋白质序列和结构。RFDiffusion是一个生成模型,使用去噪扩散概率模型创建蛋白质序列和结构[13]。RFDiffusion采用一种独特方法,通过向蛋白质3D坐标的旋转和平移矩阵独立添加高斯噪声来生成训练数据。这产生了具有更高维表示能力和全局旋转不变性的模型,从而实现了更稳定的模型训练。在去噪过程中,模型的每一步都预测局部去噪后的结构,用于下一步。然后,此预测结构用作进一步预测的初始坐标和结构模板。消融研究证实了这些模板在生成高质量蛋白质结构中的重要性。此外,RFDiffusion包含一个序列信息通道。在扩散过程中被掩蔽的序列逐渐恢复,反映了先前模型RFjoint的训练任务方法[46]。这使得RFDiffusion能够预测掩蔽字符串位置的氨基酸分布,并引发了RFDiffusion本质上可能是RFjoint进化版本、通过添加结构模板噪声增强的猜测。此外,RFDiffusion提供了针对不同任务的定制版本,例如固定已知或功能片段的结构,拓宽了其在蛋白质研究中的适用性(图5)。 图5 RFDiffusion的模型结构。使用扩散模型方法训练和微调蛋白质结构预测模型,实现蛋白质序列与结构之间隐藏关系的更精细描绘。 6.7. 药物发现中使用的对接AI工具 对接是一种计算策略,预测两个分子如何形成稳定的复合物,通常分为配体对接和蛋白质-蛋白质对接。AI提高了这一过程的速度和精度。 深度对接(DD)是一种AI赋能的方法,用于超大型化学文库的虚拟筛选,显著加速了基于结构的虚拟筛选。DD迭代对接化学文库的子集,与基于配体的预测同步,以增强虚拟命中富集,而不会大量损失潜在的药物候选分子[47]。 DiffDock是MIT开发的一种AI驱动工具,将分子对接构建为生成建模问题。它将配体姿态流形映射到对接涉及的自由度的乘积空间(平移、旋转和扭转),并在此空间上开发高效的扩散过程[14]。 7. 生成式AI:癌症药物开发的催化剂 生成式AI已成为生命科学领域的变革力量(图6),推动创新研究、优化工作流程并提供新见解。其应用广泛而多样:我们之前讨论了蛋白质的从头设计[48,49]、新型抗体的创建[50]以及单细胞多组学综合模型的构建[51],这些可以更深入地了解肿瘤中的细胞异质性,并为个性化癌症治疗的发展提供信息。 图6 生命科学中的生成式AI:应用与创新综述。生成式AI正在革新生命科学的各个方面。它加速药物发现,辅助抗体开发,并增强疾病理解的单细胞多组学模型。该技术在个性化医学、群体遗传学和病毒进化中也发挥着作用。在生物学之外,它在数据科学中用于生成合成数据,在科学可视化中通过文本到图像技术。总体而言,生成式AI的影响在生命科学中是广泛而变革性的。 此外,生成式AI还在基因组变异效应预测[52]和识别DNA序列中的统计模式[53]中发挥作用,这有助于理解癌症的遗传基础。它在预测和重建病毒进化[54]方面发挥着重要作用,从而为流行病学和疫苗开发提供有价值的见解。此外,该技术可以生成合成数据以扩充现有数据集[55],为研究人员和科学家提供宝贵资源。即使在数据可视化领域,生成式AI也可用于文本到图像生成[56,57],将复杂的文本描述转化为准确、易懂的生物图像总体而言,通过实现对生物系统的更深入理解和加速发现过程,它在推进抗癌斗争中展现出巨大前景。 8. 超越癌症:AI驱动的其他疾病药物发现 MIT的研究人员利用AI发现了一种名为“halicin”的新型抗生素,对大肠杆菌和耐药鲍曼不动杆菌有效。他们在一个包含2335种抑制大肠杆菌的分子的数据集上训练了神经网络,并通过特征工程和其他技术改进了模型。AI模型分析了超过1亿个分子,以识别针对大肠杆菌的潜在抗生素。利用模型的预测,创建了最有前景候选分子的短名单,并对其抗菌特性进行了实证测试[58]。 2020年初,Exscientia报告启动了DSP-1181的I期临床试验,该化合物旨在治疗强迫症。通过AI开发的该化合物是通过筛选化学文库中最相关的候选分子来鉴定的。据报道,DSP-1181是同类中首个进入临床试验阶段的药物[59]。这是首个进入临床试验的AI设计药物候选分子,是AI药物发现的一个关键时刻。 2023年2月,Insilico Medicine因其通过AI技术发现和开发的药物获得了FDA的首个孤儿药认定。该药物名为INS018_055,被设计为治疗特发性肺纤维化(IPF)的小分子抑制剂。利用其专有的Pharma.AI平台,Insilico不仅识别了新靶点,还生成了创新的小分子。在完成0期和I期安全性研究后,该药物现已在美国和中国进入多区域II期临床试验[60,61]。 AI已被用于寻找COVID-19疗法。研究人员将AI与基于片段的药物设计相结合,以加速识别针对SARS-CoV-2的潜在药物。利用已知的SARS-3CLpro抑制剂分子库,他们利用AI生成靶向病毒必需3CL蛋白酶的新化合物。然后筛选这些AI生成的分子,看其是否能够通过共价结合3CL蛋白酶来抑制病毒复制[46]。 在另一项研究中,深度神经网络被用于创建靶向SARS-CoV-2 3CL蛋白酶的新小分子。利用迁移学习和强化学习,对生成模型进行微调以专注于已知的蛋白酶抑制剂。训练数据来自ChEMBL病毒蛋白酶抑制剂数据库[62]。 9. 局限性与挑战 AF2在预测蛋白质三维结构方面表现出高精度,特别是当序列数据库中存在多个同源物序列以构建MSA时。然而,与其他AI工具一样,它需要大量的计算资源。这可能限制计算能力有限的研究人员对其的可及性[63]。 AI融入药物发现过程也带来了监管和实施挑战。这些包括确保数据隐私和安全、验证基于AI预测的有效性以及调整现有工作流程和系统以纳入AI工具[64]。 配体诱导折叠的挑战,特别是在蛋白质内在无序或“松散”的区域,一直是药物发现和开发中的一个重大障碍[35]。尽管AF2在蛋白质结构预测方面做出了突破性贡献,但它主要预测蛋白质的单一静态状态。这种方法忽略了酶功能和药物相互作用至关重要的动态构象变化,如结合位点的调整或结构域移动。这些动态变化对于理解蛋白质在其自然环境中的功能以及它如何与潜在药物分子相互作用至关重要[35]。 Fernández[65]的研究引入了一种深度学习方法来解决蛋白质内在无序区域中结合诱导折叠的挑战。然而,由涉及多个结构域或参与蛋白质-蛋白质相互作用的蛋白质中的药物折叠引起的构象变化仍然是一个挑战[66]。 最后,重要的是要注意,在药物发现中,理解蛋白质结构虽然具有启发性,但很少是主要瓶颈;该过程更多由来自测定、药代动力学、代谢和毒理学的经验数据驱动,强调药物发现的成功取决于多种因素。 随着蛋白质结构预测领域的不断发展,预计AI工具的准确性和适用性将取得进一步进展。这些改进可能包括在挑战性蛋白质类别和复合物上的更好性能、更好地处理蛋白质动力学和构象变化,以及减少对同源模板以进行准确预测的依赖[35]。此外,将实验约束和其他信息来源纳入建模过程可能有助于提高更广泛蛋白质靶点结构预测的准确性和可靠性。 10. 结论 AI有望显著改变药物开发的格局,提供简化流程、降低成本和提高各阶段成功率的方法。该过程始于AF2,它在预测蛋白质结构方面取得了显著成功,标志着AI在结构生物学应用中的一个里程碑。通过提供准确的蛋白质结构预测,AF2可以加速新癌症药物和疗法的开发,并更有效地识别和验证新型药物靶点,特别是对于那些缺乏大量结构信息的靶点。也许更重要的是,AF2激发了一波AI驱动的工具浪潮,涉及蛋白质结构预测、工程、对接以及生成具有所需结构和功能的新型蛋白质。这些工具例证了AI在推进药物开发中的作用,包括能够生成新型蛋白质序列和结构、预测基因组变异的影响以及提供对癌症机制的新见解。 致谢 我们感谢ChatGPT(https://chat.openai.com/)和Grammarly(https://app.grammarly.com/)在审阅我们手稿初稿方面的帮助。我们仅使用这些工具来改进写作的语法和风格。我们还感谢Midjourney(https://www.midjourney.com/)为图形摘要中使用的部分图标的生成。最后,我们感谢BioRender(https://www.biorender.com/)提供了创建本手稿中使用的图表的平台。 补充材料 以下支持信息可在https://www.mdpi.com/article/10.3390/biom14030339/s1下载,表S1。AF2、ESM2和OpenFold之间的算法比较。 作者贡献 概念化,X.Q.和A.G.;验证,X.Q.,H.L.,G.V.S.和A.G.;调查,X.Q.,H.L.,G.V.S.和A.G.;写作——原稿准备,X.Q.,H.L.,G.V.S.和A.G.;写作——审阅和编辑,X.Q.,H.L.,G.V.S.和A.G.;可视化,X.Q.和H.L.;监督,A.G.;项目管理,A.G.;资金获取,A.G.。所有作者都已阅读并同意手稿的发表版本。 利益冲突 作者声明无利益冲突。 资助声明 本综述的工作部分由NIAID合同#75N93022C00035资助。 脚注 免责声明/出版商说明:所有出版物中包含的陈述、观点和数据仅为作者和贡献者的个人观点,不代表MDPI和/或编辑的观点。MDPI和/或编辑对因内容中提及的任何想法、方法、说明、产品或财产而造成的任何伤害不承担责任。