scholarly journals Atomic-level characterization of protein–protein association

2019 ◽  
Vol 116 (10) ◽  
pp. 4244-4249 ◽  
Author(s):  
Albert C. Pan ◽  
Daniel Jacobson ◽  
Konstantin Yatsenko ◽  
Duluxan Sritharan ◽  
Thomas M. Weinreich ◽  
...  
Keyword(s):  
Structural Information ◽  
Protein Complexes ◽  
Md Simulations ◽  
Atomic Level ◽  
Conformational Ensemble ◽  
Native State ◽  
Protein Interfaces ◽  
Study Association ◽  
Functionally Diverse

Despite the biological importance of protein–protein complexes, determining their structures and association mechanisms remains an outstanding challenge. Here, we report the results of atomic-level simulations in which we observed five protein–protein pairs repeatedly associate to, and dissociate from, their experimentally determined native complexes using a molecular dynamics (MD)–based sampling approach that does not make use of any prior structural information about the complexes. To study association mechanisms, we performed additional, conventional MD simulations, in which we observed numerous spontaneous association events. A shared feature of native association for these five structurally and functionally diverse protein systems was that if the proteins made contact far from the native interface, the native state was reached by dissociation and eventual reassociation near the native interface, rather than by extensive interfacial exploration while the proteins remained in contact. At the transition state (the conformational ensemble from which association to the native complex and dissociation are equally likely), the protein–protein interfaces were still highly hydrated, and no more than 20% of native contacts had formed.

scholarly journals Atomic-level characterization of protein-protein association

2018 ◽  
Author(s):  
Albert C. Pan ◽  
Daniel Jacobson ◽  
Konstantin Yatsenko ◽  
Duluxan Sritharan ◽  
Thomas M. Weinreich ◽  
...  
Keyword(s):  
Structural Information ◽  
Protein Complexes ◽  
Md Simulations ◽  
Atomic Level ◽  
Conformational Ensemble ◽  
Native State ◽  
Protein Interfaces ◽  
Study Association ◽  
Functionally Diverse

Despite the biological importance of protein-protein complexes, determining their structures and association mechanisms remains an outstanding challenge. Here, we report the results of atomic-level simulations in which we observed five protein-protein pairs repeatedly associate to, and dissociate from, their experimentally determined native complexes using a new molecular dynamics (MD)-based sampling approach that does not make use of any prior structural information about the complexes. To study association mechanisms, we performed additional, conventional MD simulations, in which we observed numerous spontaneous association events. A shared feature of native association for these five structurally and functionally diverse protein systems was that if the proteins made contact far from the native interface, the native state was reached by dissociation and eventual re-association near the native interface, rather than by extensive interfacial exploration while the proteins remained in contact. At the transition state (the conformational ensemble from which association to the native complex and dissociation are equally likely), the protein-protein interfaces were still highly hydrated, and no more than 20% of native contacts had formed.

scholarly journals Computational design and experimental verification of a symmetric protein homodimer

2015 ◽  
Vol 112 (34) ◽  
pp. 10714-10719 ◽  
Author(s):  
Yun Mou ◽  
Po-Ssu Huang ◽  
Fang-Ciao Hsu ◽  
Shing-Jong Huang ◽  
Stephen L. Mayo
Keyword(s):  
Protein Interactions ◽  
De Novo ◽  
Computational Design ◽  
Atomic Level ◽  
Protein Interfaces ◽  
Unknown Structure ◽  
Α Helix ◽  
Distinct Features ◽  
Novel Protein

Homodimers are the most common type of protein assembly in nature and have distinct features compared with heterodimers and higher order oligomers. Understanding homodimer interactions at the atomic level is critical both for elucidating their biological mechanisms of action and for accurate modeling of complexes of unknown structure. Computation-based design of novel protein–protein interfaces can serve as a bottom-up method to further our understanding of protein interactions. Previous studies have demonstrated that the de novo design of homodimers can be achieved to atomic-level accuracy by β-strand assembly or through metal-mediated interactions. Here, we report the design and experimental characterization of a α-helix–mediated homodimer with C2 symmetry based on a monomeric Drosophila engrailed homeodomain scaffold. A solution NMR structure shows that the homodimer exhibits parallel helical packing similar to the design model. Because the mutations leading to dimer formation resulted in poor thermostability of the system, design success was facilitated by the introduction of independent thermostabilizing mutations into the scaffold. This two-step design approach, function and stabilization, is likely to be generally applicable, especially if the desired scaffold is of low thermostability.

scholarly journals Braiding topology and the energy landscape of chromosome organization proteins

2019 ◽  
Vol 117 (3) ◽  
pp. 1468-1477 ◽  
Author(s):  
Dana Krepel ◽  
Aram Davtyan ◽  
Nicholas P. Schafer ◽  
Peter G. Wolynes ◽  
José N. Onuchic
Keyword(s):  
Structural Information ◽  
Protein Complexes ◽  
Energy Landscape ◽  
Critical Role ◽  
Coiled Coil ◽  
Structural Data ◽  
Atomic Scale ◽  
Integrative Approach ◽  
Chromosome Organization ◽  
Conformational Ensemble

Assemblies of structural maintenance of chromosomes (SMC) proteins and kleisin subunits are essential to chromosome organization and segregation across all kingdoms of life. While structural data exist for parts of the SMC−kleisin complexes, complete structures of the entire complexes have yet to be determined, making mechanistic studies difficult. Using an integrative approach that combines crystallographic structural information about the globular subdomains, along with coevolutionary information and an energy landscape optimized force field (AWSEM), we predict atomic-scale structures for several tripartite SMC−kleisin complexes, including prokaryotic condensin, eukaryotic cohesin, and eukaryotic condensin. The molecular dynamics simulations of the SMC−kleisin protein complexes suggest that these complexes exist as a broad conformational ensemble that is made up of different topological isomers. The simulations suggest a critical role for the SMC coiled-coil regions, where the coils intertwine with various linking numbers. The twist and writhe of these braided coils are coupled with the motion of the SMC head domains, suggesting that the complexes may function as topological motors. Opening, closing, and translation along the DNA of the SMC−kleisin protein complexes would allow these motors to couple to the topology of DNA when DNA is entwined with the braided coils.

scholarly journals Interface Refinement of Low-to-Medium Resolution Cryo-EM Complexes using HADDOCK2.4

2021 ◽  
Author(s):  
Tim Neijenhuis ◽  
Siri C. van Keulen ◽  
Alexandre M.J.J. Bonvin
Keyword(s):  
Protein Complexes ◽  
Protein Assemblies ◽  
Cellular Processes ◽  
Protein Interfaces ◽  
Density Maps ◽  
Medium Resolution ◽  
Wide Range ◽  
Multimeric Protein

A wide range of cellular processes require the formation of multimeric protein complexes. The rise of cryo-electron microscopy (cryo-EM) has enabled the structural characterization of these protein assemblies. The produced density maps can, however, still suffer from limited resolution, impeding the process of resolving structures at atomic resolution. In order to solve this issue, monomers can be fitted into low-to-medium resolution maps. Unfortunately, the produced models frequently contain atomic clashes at the protein-protein interfaces (PPIs) as intermolecular interactions are typically not considered during monomer fitting. Here, we present a refinement approach based on HADDOCK2.4 to remove intermolecular clashes and optimize PPIs. A dataset of 14 cryo-EM complexes was used to test eight protocols. The best performing protocol, consisting of a semi-flexible simulated annealing refinement with restraints on the centroids of the monomers, was able to decrease intermolecular atomic clashes by 98% without significantly deteriorating the quality of the cryo-EM density fit.

scholarly journals Characterization of the Nuclear Export Signal in the Coronavirus Infectious Bronchitis Virus Nucleocapsid Protein

2007 ◽  
Vol 81 (8) ◽  
pp. 4298-4304 ◽  
Author(s):  
Mark L. Reed ◽  
Gareth Howell ◽  
Sally M. Harrison ◽  
Kelly-Anne Spencer ◽  
Julian A. Hiscox
Keyword(s):  
Infectious Bronchitis Virus ◽  
Nuclear Export ◽  
Structural Information ◽  
Protein Complexes ◽  
Nuclear Export Signal ◽  
Leptomycin B ◽  
N Protein ◽  
Infectious Bronchitis ◽  
Export Signal

ABSTRACT The nucleocapsid (N) protein of infectious bronchitis virus (IBV) localizes to the cytoplasm and nucleolus and contains an eight-amino-acid nucleolar retention motif. In this study, a leucine-rich nuclear export signal (NES) (291-LQLDGLHL-298) present in the C-terminal region of the IBV N protein was analyzed by using alanine substitution and deletion mutagenesis to investigate the relative contributions that leucine residues make to nuclear export and where these residues are located on the structure of the IBV N protein. The analysis indicated that Leu296 and Leu298 are required for efficient nuclear export of the protein. Structural information indicated that both of these amino acids are available for interaction with protein complexes involved in this process. However, export of N protein from the nucleus/nucleolus was not inhibited by leptomycin B treatment, indicating that N protein nuclear export is independent of the CRM1-mediated export pathway.

scholarly journals Thermal fluctuations of immature SOD1 lead to separate folding and misfolding pathways

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Ashok Sekhar ◽  
Jessica AO Rumfeldt ◽  
Helen R Broom ◽  
Colleen M Doyle ◽  
Guillaume Bouvignies ◽  
...  
Keyword(s):  
Structural Models ◽  
Thermal Fluctuations ◽  
Atomic Level ◽  
Native State ◽  
Dimer Interface ◽  
Starting Point ◽  
Dimeric Protein ◽  
Nmr Methods ◽  
Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease involving cytotoxic conformations of Cu, Zn superoxide dismutase (SOD1). A major challenge in understanding ALS disease pathology has been the identification and atomic-level characterization of these conformers. Here, we use a combination of NMR methods to detect four distinct sparsely populated and transiently formed thermally accessible conformers in equilibrium with the native state of immature SOD1 (apoSOD12SH). Structural models of two of these establish that they possess features present in the mature dimeric protein. In contrast, the other two are non-native oligomers in which the native dimer interface and the electrostatic loop mediate the formation of aberrant intermolecular interactions. Our results show that apoSOD12SH has a rugged free energy landscape that codes for distinct kinetic pathways leading to either maturation or non-native association and provide a starting point for a detailed atomic-level understanding of the mechanisms of SOD1 oligomerization.

scholarly journals Biological vs. Crystallographic Protein Interfaces: An Overview of Computational Approaches for Their Classification

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 114 ◽  
Author(s):  
Katarina Elez ◽  
Alexandre M. J. J. Bonvin ◽  
Anna Vangone
Keyword(s):  
Protein Complexes ◽  
Classification Problem ◽  
Empirical Knowledge ◽  
Comprehensive Overview ◽  
X Ray ◽  
Biologically Relevant ◽  
X Ray Crystallography ◽  
The Past ◽  
Protein Interfaces

Complexes between proteins are at the basis of almost every process in cells. Their study, from a structural perspective, has a pivotal role in understanding biological functions and, importantly, in drug development. X-ray crystallography represents the broadest source for the experimental structural characterization of protein-protein complexes. Correctly identifying the biologically relevant interface from the crystallographic ones is, however, not trivial and can be prone to errors. Over the past two decades, computational methodologies have been developed to study the differences of those interfaces and automatically classify them as biological or crystallographic. Overall, protein-protein interfaces show differences in terms of composition, energetics and evolutionary conservation between biological and crystallographic ones. Based on those observations, a number of computational methods have been developed for this classification problem, which can be grouped into three main categories: Energy-, empirical knowledge- and machine learning-based approaches. In this review, we give a comprehensive overview of the training datasets and methods so far implemented, providing useful links and a brief description of each method.

Rapid Online Buffer Exchange: A Method for Screening of Proteins, Protein Complexes, and Cell Lysates by Native Mass Spectrometry

2019 ◽  
Author(s):  
Zachary VanAernum ◽  
Florian Busch ◽  
Benjamin J. Jones ◽  
Mengxuan Jia ◽  
Zibo Chen ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Speed ◽  
Structural Information ◽  
Protein Complexes ◽  
High Sensitivity ◽  
Native Mass Spectrometry ◽  
Structural Features ◽  
Consumer Products ◽  
Cell Lysates ◽  
Protein Expression And Purification

It is important to assess the identity and purity of proteins and protein complexes during and after protein purification to ensure that samples are of sufficient quality for further biochemical and structural characterization, as well as for use in consumer products, chemical processes, and therapeutics. Native mass spectrometry (nMS) has become an important tool in protein analysis due to its ability to retain non-covalent interactions during measurements, making it possible to obtain protein structural information with high sensitivity and at high speed. Interferences from the presence of non-volatiles are typically alleviated by offline buffer exchange, which is timeconsuming and difficult to automate. We provide a protocol for rapid online buffer exchange (OBE) nMS to directly screen structural features of pre-purified proteins, protein complexes, or clarified cell lysates. Information obtained by OBE nMS can be used for fast (<5 min) quality control and can further guide protein expression and purification optimization.

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