Pub Date : 2025-09-19DOI: 10.1016/j.sbi.2025.103154
Zilong Li , Stephanie Portillo-Ledesma , Tamar Schlick
Specific values of nucleosome spacing have long been associated with distinct chromatin organization, but recent studies reveal surprising structural and functional consequences of small changes in regular linker DNA length. This opinion article revisits experimental and modeling studies addressing the classic 10n versus 10n + 5 spacing, highlighting how this 5 bp difference can alter nucleosome orientation, fiber topology, and higher-order chromatin behavior. We underscore how differences in model parameters and system design yield different trends for the effect of linker DNA lengths on chromatin architecture. However, chromatin structure in vivo reflects the heterogeneous nucleosome spacing in combination with other cellular variables like salt conditions, epigenetic marks, and protein and RNA binding, which work together to shape gene folding and direct gene regulation.
{"title":"Chromatin higher-order folding as influenced by preferred values of linker DNA","authors":"Zilong Li , Stephanie Portillo-Ledesma , Tamar Schlick","doi":"10.1016/j.sbi.2025.103154","DOIUrl":"10.1016/j.sbi.2025.103154","url":null,"abstract":"<div><div>Specific values of nucleosome spacing have long been associated with distinct chromatin organization, but recent studies reveal surprising structural and functional consequences of small changes in regular linker DNA length. This opinion article revisits experimental and modeling studies addressing the classic 10<em>n</em> versus 10<em>n</em> + 5 spacing, highlighting how this 5 bp difference can alter nucleosome orientation, fiber topology, and higher-order chromatin behavior. We underscore how differences in model parameters and system design yield different trends for the effect of linker DNA lengths on chromatin architecture. However, chromatin structure <em>in vivo</em> reflects the heterogeneous nucleosome spacing in combination with other cellular variables like salt conditions, epigenetic marks, and protein and RNA binding, which work together to shape gene folding and direct gene regulation.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103154"},"PeriodicalIF":6.1,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-17DOI: 10.1016/j.sbi.2025.103158
Ran Friedman
The rapid evolution of microorganisms and cancer cells makes it difficult to treat tumours and infectious diseases, because resistance to drugs is the rule rather than the exception. Structures or models of protein–drug complexes help to understand how mutations lead to resistance and to design better drugs. However, it is difficult to reason how small changes in the structure lead to drug resistance. Thus, protein and drug dynamics need to be considered. Strategies to increase drug residence are sought after to increase the efficacy of drugs. Computational methods to calculate the effect of mutations on drug binding and residence times are being developed and improved, but are challenging. A priori prediction of a mutation's effect on drug binding is an even greater challenge. On the other hand, knowledge about protein–drug complexes has led to the development of multiple design strategies that aim to reduce mutation-driven drug resistance.
{"title":"Resistance mutations, drug binding and drug residence times","authors":"Ran Friedman","doi":"10.1016/j.sbi.2025.103158","DOIUrl":"10.1016/j.sbi.2025.103158","url":null,"abstract":"<div><div>The rapid evolution of microorganisms and cancer cells makes it difficult to treat tumours and infectious diseases, because resistance to drugs is the rule rather than the exception. Structures or models of protein–drug complexes help to understand how mutations lead to resistance and to design better drugs. However, it is difficult to reason how small changes in the structure lead to drug resistance. Thus, protein and drug dynamics need to be considered. Strategies to increase drug residence are sought after to increase the efficacy of drugs. Computational methods to calculate the effect of mutations on drug binding and residence times are being developed and improved, but are challenging. A priori prediction of a mutation's effect on drug binding is an even greater challenge. On the other hand, knowledge about protein–drug complexes has led to the development of multiple design strategies that aim to reduce mutation-driven drug resistance.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103158"},"PeriodicalIF":6.1,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145085329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-15DOI: 10.1016/j.sbi.2025.103155
Vanessa Leone , Fabrizio Marinelli
Protein function arises from the interplay of structure, dynamics, and biomolecular interactions. Despite advances in cryo-EM and AI-based structure prediction, capturing dynamic and energetic features remains a challenge. Biophysical methods like NMR, EPR, HDX-MS, SAXS, and cryo-EM provide valuable but often indirect signals. Connecting these to molecular mechanisms requires integrative approaches that combine experiments with physics-based simulations, revealing both stable structures and transient, functionally important intermediates. This review highlights recent advances in integrative modeling using the maximum entropy principle to build dynamic ensembles from diverse data while addressing uncertainty and bias. These methods help resolve heterogeneity and interpret low-resolution data. We conclude by exploring how integrative modeling, enhanced sampling, and AI-driven tools enable new insights into slow, large-scale conformational changes.
{"title":"From snapshots to ensembles: Integrating experimental data and dynamics","authors":"Vanessa Leone , Fabrizio Marinelli","doi":"10.1016/j.sbi.2025.103155","DOIUrl":"10.1016/j.sbi.2025.103155","url":null,"abstract":"<div><div>Protein function arises from the interplay of structure, dynamics, and biomolecular interactions. Despite advances in cryo-EM and AI-based structure prediction, capturing dynamic and energetic features remains a challenge. Biophysical methods like NMR, EPR, HDX-MS, SAXS, and cryo-EM provide valuable but often indirect signals. Connecting these to molecular mechanisms requires integrative approaches that combine experiments with physics-based simulations, revealing both stable structures and transient, functionally important intermediates. This review highlights recent advances in integrative modeling using the maximum entropy principle to build dynamic ensembles from diverse data while addressing uncertainty and bias. These methods help resolve heterogeneity and interpret low-resolution data. We conclude by exploring how integrative modeling, enhanced sampling, and AI-driven tools enable new insights into slow, large-scale conformational changes.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103155"},"PeriodicalIF":6.1,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Enzymes effectively catalyze chemical reactions at their active sites. The reactions involve three microscopic events at the active sites: substrate binding, multi-step chemical reactions, and product release. These events are often coupled with enzyme conformational changes, making theoretical and computational analyses more challenging. Advanced molecular simulations, involving molecular dynamics (MD) and hybrid quantum mechanics/molecular mechanics (QM/MM), are now utilized to investigate the functions of enzymes such as tryptophan synthase and P-type ATPases. Here, we summarize recent multiscale molecular simulations that incorporate multiple microscopic events in enzyme functions. The coupling of enzyme conformational changes and chemical reactions can predict a proper direction in enzymatic reaction cycles, which requires accurate predictions of the free energy changes between different physiological states. Using machine learning (ML) methods, all the microscopic events in enzyme catalysis could be described with the same accuracy as quantum chemistry. We also discuss recent developments in ML/MM simulations for enzyme catalysis.
{"title":"Toward understanding whole enzymatic reaction cycles using multi-scale molecular simulations","authors":"Shingo Ito , Chigusa Kobayashi , Kiyoshi Yagi , Yuji Sugita","doi":"10.1016/j.sbi.2025.103153","DOIUrl":"10.1016/j.sbi.2025.103153","url":null,"abstract":"<div><div>Enzymes effectively catalyze chemical reactions at their active sites. The reactions involve three microscopic events at the active sites: substrate binding, multi-step chemical reactions, and product release. These events are often coupled with enzyme conformational changes, making theoretical and computational analyses more challenging. Advanced molecular simulations, involving molecular dynamics (MD) and hybrid quantum mechanics/molecular mechanics (QM/MM), are now utilized to investigate the functions of enzymes such as tryptophan synthase and P-type ATPases. Here, we summarize recent multiscale molecular simulations that incorporate multiple microscopic events in enzyme functions. The coupling of enzyme conformational changes and chemical reactions can predict a proper direction in enzymatic reaction cycles, which requires accurate predictions of the free energy changes between different physiological states. Using machine learning (ML) methods, all the microscopic events in enzyme catalysis could be described with the same accuracy as quantum chemistry. We also discuss recent developments in ML/MM simulations for enzyme catalysis.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103153"},"PeriodicalIF":6.1,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145047693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-10DOI: 10.1016/j.sbi.2025.103152
Viet-Khoa Tran-Nguyen, Anne-Claude Camproux
Protein-ligand modeling is a cornerstone of modern drug discovery, facilitating the identification and optimization of bioactive compounds that modulate protein function. Computational approaches provide cost-effective and scalable strategies for exploring the growing chemical and biological spaces, accelerating early-stage drug development. Advances in both physics-based methods and data-driven machine learning techniques have expanded the range and accuracy of tools available for modeling protein-ligand interactions. This review provides a current and concise view of key methodologies in protein-ligand modeling, including binding site prediction and the generation and evaluation of target-bound ligand conformations. It also discusses state-of-the-art machine learning approaches that are reshaping how these tasks are performed and enhancing the accuracy of binding site, binding pose, and binding affinity predictions.
{"title":"Computational modeling of protein–ligand interactions: From binding site identification to pose prediction and beyond","authors":"Viet-Khoa Tran-Nguyen, Anne-Claude Camproux","doi":"10.1016/j.sbi.2025.103152","DOIUrl":"10.1016/j.sbi.2025.103152","url":null,"abstract":"<div><div>Protein-ligand modeling is a cornerstone of modern drug discovery, facilitating the identification and optimization of bioactive compounds that modulate protein function. Computational approaches provide cost-effective and scalable strategies for exploring the growing chemical and biological spaces, accelerating early-stage drug development. Advances in both physics-based methods and data-driven machine learning techniques have expanded the range and accuracy of tools available for modeling protein-ligand interactions. This review provides a current and concise view of key methodologies in protein-ligand modeling, including binding site prediction and the generation and evaluation of target-bound ligand conformations. It also discusses state-of-the-art machine learning approaches that are reshaping how these tasks are performed and enhancing the accuracy of binding site, binding pose, and binding affinity predictions.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103152"},"PeriodicalIF":6.1,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145027162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-10DOI: 10.1016/j.sbi.2025.103151
Kexin Xu , Jingxuan Ge , Rongfan Tang , Tingjun Hou , Huiyong Sun
Proteolysis-targeting chimeras (PROTACs) achieve irreversible clearance of target proteins by hijacking the ubiquitin–proteasome system, breaking the design paradigm of traditional inhibitory drugs. The development of computational approaches has effectively promoted the rational design of PROTACs, yet existing methods mainly focus on predicting the static structure of PROTAC systems, with methodological gaps in analyzing their dynamic characteristics. Knowing that the dynamic behaviors can dramatically influence the stability and degradation efficacy of a PROTAC system, we systematically summarize the recent progresses of using structure-based and structure–artificial intelligence–hybrid methodologies for characterizing the dynamic behaviors of PROTAC systems, with a focus on elucidating the dynamic characteristics of target protein–PROTAC–E3 ligase ternary structures and prediction of their key properties.
{"title":"Dynamic characteristics of proteolysis-targeting chimera systems revealed by in silico computations","authors":"Kexin Xu , Jingxuan Ge , Rongfan Tang , Tingjun Hou , Huiyong Sun","doi":"10.1016/j.sbi.2025.103151","DOIUrl":"10.1016/j.sbi.2025.103151","url":null,"abstract":"<div><div>Proteolysis-targeting chimeras (PROTACs) achieve irreversible clearance of target proteins by hijacking the ubiquitin–proteasome system, breaking the design paradigm of traditional inhibitory drugs. The development of computational approaches has effectively promoted the rational design of PROTACs, yet existing methods mainly focus on predicting the static structure of PROTAC systems, with methodological gaps in analyzing their dynamic characteristics. Knowing that the dynamic behaviors can dramatically influence the stability and degradation efficacy of a PROTAC system, we systematically summarize the recent progresses of using structure-based and structure–artificial intelligence–hybrid methodologies for characterizing the dynamic behaviors of PROTAC systems, with a focus on elucidating the dynamic characteristics of target protein–PROTAC–E3 ligase ternary structures and prediction of their key properties.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103151"},"PeriodicalIF":6.1,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145039512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-09DOI: 10.1016/j.sbi.2025.103150
Marcela de Barros, Gregory Labrie, Carla Mattos
Our previously proposed Ras dimerization model is consistent with recent details observed by NMR in that Raf activation is centered on the Ras/Raf dimer, distinct from one in which Ras activates Raf as a monomer with the Raf cysteine rich domain inserted in the membrane. We review mechanistic understanding of Raf activation within nanoclusters of Ras on the membrane, with a shift to dimers upon binding Raf. This sets the stage for a signaling platform composed of Ras/Raf and Galectin dimers that facilitates the release of Raf autoinhibition and folding of the Raf intrinsically disordered region between the Ras-binding domains and the kinase bound to 14-3-3 and MEK. This platform could provide synchronized units for signal amplification and is consistent with a Ras stationary phase observed in cells.
{"title":"Ras/Raf dimerization model for activation of Raf kinase","authors":"Marcela de Barros, Gregory Labrie, Carla Mattos","doi":"10.1016/j.sbi.2025.103150","DOIUrl":"10.1016/j.sbi.2025.103150","url":null,"abstract":"<div><div>Our previously proposed Ras dimerization model is consistent with recent details observed by NMR in that Raf activation is centered on the Ras/Raf dimer, distinct from one in which Ras activates Raf as a monomer with the Raf cysteine rich domain inserted in the membrane. We review mechanistic understanding of Raf activation within nanoclusters of Ras on the membrane, with a shift to dimers upon binding Raf. This sets the stage for a signaling platform composed of Ras/Raf and Galectin dimers that facilitates the release of Raf autoinhibition and folding of the Raf intrinsically disordered region between the Ras-binding domains and the kinase bound to 14-3-3 and MEK. This platform could provide synchronized units for signal amplification and is consistent with a Ras stationary phase observed in cells.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"95 ","pages":"Article 103150"},"PeriodicalIF":6.1,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-29DOI: 10.1016/j.sbi.2025.103149
Ruth Nussinov , Hyunbum Jang
Drug residence time defines the duration the drug is bound to its protein target. It is a crucial determinant of drug action. Yet, a priori estimating it in the design could be the most challenging. The mechanisms of allosteric and orthosteric drugs differ in how they affect it. Binding at the active site, the residence time of orthosteric drugs is primarily affected by binding kinetics, which is not the case for allosteric drugs. Allosteric drugs determine the orthosteric drug residence time by the nature and extent of the population shift that they promote, which modulate the active site conformation. However, cooperative binding is bidirectional; orthosteric drug binding at the active site can increase (decrease) residence time at the allosteric site.
{"title":"How residence time works in allosteric drugs","authors":"Ruth Nussinov , Hyunbum Jang","doi":"10.1016/j.sbi.2025.103149","DOIUrl":"10.1016/j.sbi.2025.103149","url":null,"abstract":"<div><div>Drug residence time defines the duration the drug is bound to its protein target. It is a crucial determinant of drug action. Yet, <em>a priori</em> estimating it in the design could be the most challenging. The mechanisms of allosteric and orthosteric drugs differ in how they affect it. Binding at the active site, the residence time of orthosteric drugs is primarily affected by binding kinetics, which is not the case for allosteric drugs. Allosteric drugs determine the orthosteric drug residence time by the nature and extent of the population shift that they promote, which modulate the active site conformation. However, cooperative binding is bidirectional; orthosteric drug binding at the active site can increase (decrease) residence time at the allosteric site.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"94 ","pages":"Article 103149"},"PeriodicalIF":6.1,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144913149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-08-23DOI: 10.1016/j.sbi.2025.103139
Reza Dastvan , Stefan Stoll
This perspective highlights recent applications and technological progress in dipolar electron paramagnetic resonance (EPR) spectroscopy, including double electron–electron resonance (DEER) spectroscopy. These methods provide nanoscale distance distributions between site-specific spin labels in biomacromolecules. The resulting data are particularly well suited for quantifying the structure and energetics of conformational ensembles of multi-state and flexible proteins. Recent applications span a wide range of systems and are accompanied by innovations in spin labeling, deuteration, in-cell measurements, integrative multi-technique approaches, and novel computational modeling methods combined with structure prediction tools.
{"title":"Recent advances in quantifying protein conformational ensembles with dipolar EPR spectroscopy","authors":"Reza Dastvan , Stefan Stoll","doi":"10.1016/j.sbi.2025.103139","DOIUrl":"10.1016/j.sbi.2025.103139","url":null,"abstract":"<div><div>This perspective highlights recent applications and technological progress in dipolar electron paramagnetic resonance (EPR) spectroscopy, including double electron–electron resonance (DEER) spectroscopy. These methods provide nanoscale distance distributions between site-specific spin labels in biomacromolecules. The resulting data are particularly well suited for quantifying the structure and energetics of conformational ensembles of multi-state and flexible proteins. Recent applications span a wide range of systems and are accompanied by innovations in spin labeling, deuteration, in-cell measurements, integrative multi-technique approaches, and novel computational modeling methods combined with structure prediction tools.</div></div>","PeriodicalId":10887,"journal":{"name":"Current opinion in structural biology","volume":"94 ","pages":"Article 103139"},"PeriodicalIF":6.1,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144889508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}