@article {2015|1657, title = {Changes in protein structure at the interface accompanying complex formation.}, journal = {Iucrj}, volume = {2}, number = {Pt 6}, year = {2015}, month = {nov}, pages = {643{\textendash}652}, publisher = {Department of Biochemistry, Bose Institute , P-1/12 CIT Scheme VIIM, Kolkata 700 054, India.}, abstract = {Protein interactions are essential in all biological processes. The changes brought about in the structure when a free component forms a complex with another molecule need to be characterized for a proper understanding of molecular recognition as well as for the successful implementation of docking algorithms. Here, unbound (U) and bound (B) forms of protein structures from the Protein-Protein Interaction Affinity Database are compared in order to enumerate the changes that occur at the interface atoms/residues in terms of the solvent-accessible surface area (ASA), secondary structure, temperature factors (B factors) and disorder-to-order transitions. It is found that the interface atoms optimize contacts with the atoms in the partner protein, which leads to an increase in their ASA in the bound interface in the majority (69\%) of the proteins when compared with the unbound interface, and this is independent of the root-mean-square deviation between the U and B forms. Changes in secondary structure during the transition indicate a likely extension of helices and strands at the expense of turns and coils. A reduction in flexibility during complex formation is reflected in the decrease in B factors of the interface residues on going from the U form to the B form. There is, however, no distinction in flexibility between the interface and the surface in the monomeric structure, thereby highlighting the potential problem of using B factors for the prediction of binding sites in the unbound form for docking another protein. 16\% of the proteins have missing (disordered) residues in the U form which are observed (ordered) in the B form, mostly with an irregular conformation; the data set also shows differences in the composition of interface and non-interface residues in the disordered polypeptide segments as well as differences in their surface burial.}, doi = {10.1107/S2052252515015250}, author = {Chakravarty, Devlina and Janin, Jo{\"e}l and Charles H. Robert and Chakrabarti, Pinak} } @article {2015|1679, title = {Conformational ensembles and sampled landscapes: analysis and comparison}, journal = {J. Comp. Chem.}, volume = {36}, year = {2015}, pages = {1213{\textendash}31}, author = {Fr{\'e}d{\'e}ric Cazals and A Roth and T Dreyfus and D Mazauric and Charles H. Robert} } @article {2011|1665, title = {Community-wide assessment of protein-interface modeling suggests improvements to design methodology.}, journal = {J. Mol. Biol.}, volume = {414}, year = {2011}, month = {nov}, pages = {289{\textendash}302}, abstract = {

The CAPRI (Critical Assessment of Predicted Interactions) and CASP (Critical Assessment of protein Structure Prediction) experiments have demonstrated the power of community-wide tests of methodology in assessing the current state of the art and spurring progress in the very challenging areas of protein docking and structure prediction. We sought to bring the power of community-wide experiments to bear on a very challenging protein design problem that provides a complementary but equally fundamental test of current understanding of protein-binding thermodynamics. We have generated a number of designed protein-protein interfaces with very favorable computed binding energies but which do not appear to be formed in experiments, suggesting that there may be important physical chemistry missing in the energy calculations. A total of 28 research groups took up the challenge of determining what is missing: we provided structures of 87 designed complexes and 120 naturally occurring complexes and asked participants to identify energetic contributions and/or structural features that distinguish between the two sets. The community found that electrostatics and solvation terms partially distinguish the designs from the natural complexes, largely due to the nonpolar character of the designed interactions. Beyond this polarity difference, the community found that the designed binding surfaces were, on average, structurally less embedded in the designed monomers, suggesting that backbone conformational rigidity at the designed surface is important for realization of the designed function. These results can be used to improve computational design strategies, but there is still much to be learned; for example, one designed complex, which does form in experiments, was classified by all metrics as a nonbinder.

}, keywords = {Binding Sites, Models, Molecular, Protein Binding, Proteins}, issn = {1089-8638}, doi = {10.1016/j.jmb.2011.09.031}, author = {Fleishman, Sarel J and Whitehead, Timothy A and Strauch, Eva-Maria and Corn, Jacob E and Qin, Sanbo and Zhou, Huan-Xiang and Mitchell, Julie C and Demerdash, Omar N A and Takeda-Shitaka, Mayuko and Terashi, Genki and Moal, Iain H and Li, Xiaofan and Bates, Paul A and Martin Zacharias and Park, Hahnbeom and Ko, Jun-su and Lee, Hasup and Seok, Chaok and Bourquard, Thomas and Bernauer, Julie and Poupon, Anne and Az{\'e}, J{\'e}r{\^o}me and Soner, Seren and Ovali, Sefik Kerem and Ozbek, Pemra and Tal, Nir Ben and Haliloglu, T{\"u}rkan and Hwang, Howook and Vreven, Thom and Pierce, Brian G and Weng, Zhiping and P{\'e}rez-Cano, Laura and Pons, Carles and Fern{\'a}ndez-Recio, Juan and Jiang, Fan and Yang, Feng and Gong, Xinqi and Cao, Libin and Xu, Xianjin and Liu, Bin and Wang, Panwen and Li, Chunhua and Wang, Cunxin and Charles H. Robert and Guharoy, Mainak and Liu, Shiyong and Huang, Yangyu and Li, Lin and Guo, Dachuan and Chen, Ying and Xiao, Yi and London, Nir and Itzhaki, Zohar and Schueler-Furman, Ora and Inbar, Yuval and Potapov, Vladimir and Cohen, Mati and Schreiber, Gideon and Tsuchiya, Yuko and Kanamori, Eiji and Standley, Daron M and Nakamura, Haruki and Kinoshita, Kengo and Driggers, Camden M and Hall, Robert G and Morgan, Jessica L and Hsu, Victor L and Zhan, Jian and Yang, Yuedong and Zhou, Yaoqi and Kastritis, Panagiotis L and Bonvin, Alexandre M J J and Zhang, Weiyi and Camacho, Carlos J and Kilambi, Krishna P and Sircar, Aroop and Gray, Jeffrey J and Ohue, Masahito and Uchikoga, Nobuyuki and Matsuzaki, Yuri and Ishida, Takashi and Akiyama, Yutaka and Khashan, Raed and Bush, Stephen and Fouches, Denis and Tropsha, Alexander and Esquivel-Rodr{\'\i}guez, Juan and Kihara, Daisuke and Stranges, P Benjamin and Jacak, Ron and Kuhlman, Brian and Huang, Sheng-You and Zou, Xiaoqin and Wodak, Shoshana J and Janin, Jo{\"e}l and Baker, David} } @article {2010|1749, title = {A computational study of a recreated {G} protein-{GEF} reaction intermediate competent for nucleotide exchange: fate of the {M}g ion}, journal = {Plos One}, volume = {5}, number = {2}, year = {2010}, month = {feb}, pages = {e9142}, publisher = {Public Library of Science}, abstract = {

Small G-proteins of the superfamily Ras function as molecular switches, interacting with different cellular partners according to their activation state. G-protein activation involves the dissociation of bound GDP and its replacement by GTP, in an exchange reaction that is accelerated and regulated in the cell by guanine-nucleotide exchange factors (GEFs). Large conformational changes accompany the exchange reaction, and our understanding of the mechanism is correspondingly incomplete. However, much knowledge has been derived from structural studies of blocked or inactive mutant GEFs, which presumably closely represent intermediates in the exchange reaction and yet which are by design incompetent for carrying out the nucleotide exchange reaction. In this study we have used comparative modelling to recreate an exchange-competent form of a late, pre-GDP-ejection intermediate species in Arf1, a well-characterized small G-protein. We extensively characterized three distinct models of this intermediate using molecular dynamics simulations, allowing us to address ambiguities related to the mutant structural studies. We observed in particular the unfavorable nature of Mg2+ associated forms of the complex and the establishment of closer Arf1-GEF contacts in its absence. The results of this study shed light on GEF-mediated activation of this small G protein and on predicting the fate of the Mg ion at a critical point in the exchange reaction. The structural models themselves furnish additional targets for interfacial inhibitor design, a promising direction for exploring potentially druggable targets with high biological specificity.

}, doi = {10.1371/journal.pone.0009142}, url = {http://dx.doi.org/10.1371\%2Fjournal.pone.0009142}, author = {M{\'e}riam Ben Hamida{\textendash}Reba\"{\i} and Charles H. Robert} } @article {2010|1736, title = {Consensus {M}odes, a robust description of protein collective motions from multiple-minima normal mode analysis{\textendash}application to the {HIV}-1 protease.}, journal = {Phys. Chem. Chem. Phys.}, volume = {12}, year = {2010}, month = {mar}, pages = {2850{\textendash}2859}, abstract = {

Protein flexibility is essential for enzymatic function, ligand binding, and protein-protein or protein-nucleic acid interactions. Normal mode analysis has increasingly been shown to be well suited for studying such flexibility, as it can be used to identify favorable structural deformations that correspond to functional motions. However, normal modes are strictly relevant to a single structure, reflecting a particular minimum on a complex energy surface, and are thus susceptible to artifacts. We describe a new theoretical framework for determining \"consensus\" normal modes from a set of related structures, such as those issuing from a short molecular dynamics simulation. This approach is more robust than standard normal mode analysis, and provides higher collectivity and symmetry properties. In an application to HIV-1 protease, the low-frequency consensus modes describe biologically relevant motions including flap opening and closing that can be used in interpreting structural changes accompanying the binding of widely differing inhibitors.

}, doi = {10.1039/b919148h}, author = {Paulo R. Batista and Charles H. Robert and Jean-Didier Mar{\'e}chal and M{\'e}riam Ben Hamida{\textendash}Reba\"{\i} and Paulo Pascutti and Paulo M. Bisch and David P. Perahia} } @article {1997|1680, title = {Collective-variable Monte Carlo simulation of DNA}, journal = {J. Comp. Chem.}, volume = {18}, year = {1997}, pages = {2001{\textendash}2011}, author = {H. Gabb and Chantal Pr{\'e}vost and G. Bertucat and Charles H. Robert and Richard Lavery} } @article {1991|1593, title = {A combined study of aggregation, membrane affinity and pore activity of natural and modified melittin}, journal = {Biochim. Biophys. Acta}, volume = {1069}, number = {1}, year = {1991}, month = {oct}, pages = {77{\textendash}86}, author = {Stankowski, S and Pawlak, M and Kaisheva, E and Charles H. Robert and Schwarz, G} } @inbook {1987, title = {Calorimetric analysis of oxygen binding to lobster hemocyanin}, booktitle = {Invertebrate Oxygen Carriers}, year = {1987}, publisher = {Springer-Verlag}, organization = {Springer-Verlag}, address = {Berlin}, author = {Parody-Morreale, A. and Robert, C. H. and Gill, S. J.} } @article {1987|1818, title = {Calorimetric studies of oxygen and carbon monoxide binding to human hemoglobin. Sequential binding heats for oxygen}, journal = {J. Biol. Chem.}, volume = {262}, number = {23}, year = {1987}, month = {aug}, pages = {10994{\textendash}10999}, author = {Parody-Morreale, A and Robert, C H and Bishop, G A and Gill, S J} } @article {1987|1820, title = {Carbon dioxide and oxygen linkage in human hemoglobin tetramers}, journal = {J. Mol. Biol.}, volume = {196}, number = {4}, year = {1987}, month = {aug}, pages = {927{\textendash}934}, author = {Doyle, M L and Di Cera, E and Robert, C H and Gill, S J} } @article {1986|1602, title = {Cooperative free energies for nested allosteric models as applied to human hemoglobin}, journal = {Biophys. J.}, volume = {50}, number = {4}, year = {1986}, month = {oct}, pages = {747{\textendash}752}, author = {Gill, S J and Charles H. Robert and Coletta, M and Di Cera, E and Brunori, M} }