@article {2014|1792, title = {Allosteric regulation of pentameric ligand-gated ion channels: An emerging mechanistic perspective}, journal = {Channels}, volume = {8}, number = {4}, year = {2014}, pages = {350{\textendash}360}, keywords = {Allosteric Regulation, Animals, chemistry/metabolism, Humans, Ion Channel Gating, Ligand-Gated Ion Channels, metabolism, Models, Molecular, Protein Multimerization, Small Molecule Libraries}, author = {Antoine Taly and J{\'e}r{\^o}me H{\'e}nin and Changeux, Jean-Pierre and Cecchini, Marco} } @article {2014|1751, title = {How force unfolding differs from chemical denaturation.}, journal = {Proc. Natl. Acad. Sci. U.s.a}, volume = {111}, year = {2014}, pages = {3413{\textendash}8}, abstract = {

Single-molecule force spectroscopies are remarkable tools for studying protein folding and unfolding, but force unfolding explores protein configurations that are potentially very different from the ones traditionally explored in chemical or thermal denaturation. Understanding these differences is crucial because such configurations serve as starting points of folding studies, and thus can affect both the folding mechanism and the kinetics. Here we provide a detailed comparison of both chemically induced and force-induced unfolded state ensembles of ubiquitin based on extensive, all-atom simulations of the protein either extended by force or denatured by urea. As expected, the respective unfolded states are very different on a macromolecular scale, being fully extended under force with no contacts and partially extended in urea with many nonnative contacts. The amount of residual secondary structure also differs: A significant population of $\alpha$-helices is found in chemically denatured configurations but such helices are absent under force, except at the lowest applied force of 30 pN where short helices form transiently. We see that typical-size helices are unstable above this force, and $\beta$-sheets cannot form. More surprisingly, we observe striking differences in the backbone dihedral angle distributions for the protein unfolded under force and the one unfolded by denaturant. A simple model based on the dialanine peptide is shown to not only provide an explanation for these striking differences but also illustrates how the force dependence of the protein dihedral angle distributions give rise to the worm-like chain behavior of the chain upon force.

}, keywords = {Chemical, Hydrogen-Ion Concentration, Models, Molecular Dynamics Simulation, Protein Conformation, Protein Denaturation, Protein Folding, Protein Unfolding, Ubiquitin, Ubiquitin: chemistry, Urea, Urea: chemistry}, issn = {1091-6490}, url = {http://www.ncbi.nlm.nih.gov/pubmed/24550471}, author = {Guillaume Stirnemann and Kang, Seung-gu and Zhou, Ruhong and Berne, Bruce J} } @article {2013|1752, title = {Elasticity, structure, and relaxation of extended proteins under force.}, journal = {Proc. Natl. Acad. Sci. U.s.a}, volume = {110}, year = {2013}, pages = {3847{\textendash}52}, abstract = {

Force spectroscopies have emerged as a powerful and unprecedented tool to study and manipulate biomolecules directly at a molecular level. Usually, protein and DNA behavior under force is described within the framework of the worm-like chain (WLC) model for polymer elasticity. Although it has been surprisingly successful for the interpretation of experimental data, especially at high forces, the WLC model lacks structural and dynamical molecular details associated with protein relaxation under force that are key to the understanding of how force affects protein flexibility and reactivity. We use molecular dynamics simulations of ubiquitin to provide a deeper understanding of protein relaxation under force. We find that the WLC model successfully describes the simulations of ubiquitin, especially at higher forces, and we show how protein flexibility and persistence length, probed in the force regime of the experiments, are related to how specific classes of backbone dihedral angles respond to applied force. Although the WLC model is an average, backbone model, we show how the protein side chains affect the persistence length. Finally, we find that the diffusion coefficient of the protein{\textquoteright}s end-to-end distance is on the order of 10(8) nm(2)/s, is position and side-chain dependent, but is independent of the length and independent of the applied force, in contrast with other descriptions.

}, keywords = {Atomic Force, Biophysical Phenomena, Computer Simulation, Elasticity, Mechanical, Microscopy, Models, Molecular, Molecular Dynamics Simulation, Proteins, Proteins: chemistry, Stress, Ubiquitin, Ubiquitin: chemistry}, issn = {1091-6490}, url = {http://www.pnas.org/content/early/2013/02/13/1300596110.abstract}, author = {Guillaume Stirnemann and Giganti, David and Fernandez, Julio M and Berne, B J} } @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|1789, title = {Single-spanning transmembrane domains in cell growth and cell-cell interactions: More than meets the eye?}, journal = {Cell Adh. Migr.}, volume = {4}, number = {2}, year = {2010}, month = {apr}, pages = {313{\textendash}324}, abstract = {

As a whole, integral membrane proteins represent about one third of sequenced genomes, and more than 50\% of currently available drugs target membrane proteins, often cell surface receptors. Some membrane protein classes, with a defined number of transmembrane (TM) helices, are receiving much attention because of their great functional and pharmacological importance, such as G protein-coupled receptors possessing 7 TM segments. Although they represent roughly half of all membrane proteins, bitopic proteins (with only 1 TM helix) have so far been less well characterized. Though they include many essential families of receptors, such as adhesion molecules and receptor tyrosine kinases, many of which are excellent targets for biopharmaceuticals (peptides, antibodies, et al.). A growing body of evidence suggests a major role for interactions between TM domains of these receptors in signaling, through homo and heteromeric associations, conformational changes, assembly of signaling platforms, etc. Significantly, mutations within single domains are frequent in human disease, such as cancer or developmental disorders. This review attempts to give an overview of current knowledge about these interactions, from structural data to therapeutic perspectives, focusing on bitopic proteins involved in cell signaling.

}, keywords = {Animals, Biological, Humans, Membrane Proteins, Models, Protein Structure, Secondary, Signal Transduction, Tertiary}, issn = {1933-6926}, doi = {10.4161/cam.4.2.12430}, author = {Pierre Hubert and Paul Sawma and Jean-Pierre Duneau and Jonathan Khao and J{\'e}r{\^o}me H{\'e}nin and Dominique Bagnard and James Sturgis} } @article {2009|2018, title = {Energy Flow and Long-Range Correlations in Guanine-Binding Riboswitch: A Nonequilibrium Molecular Dynamics Study}, journal = {J. Phys. Chem. B}, volume = {113}, number = {27}, year = {2009}, month = {jul}, pages = {9340{\textendash}9347}, keywords = {Binding Sites, Computer Simulation, Energy Transfer, Guanine, Ligands, Models, Molecular, Nucleic Acid Conformation, RNA, Temperature}, doi = {10.1021/jp902013s}, author = {Phuong Hoang Nguyen and Philippe Derreumaux and Stock, Gerhard} } @article {2009|1864, title = {Models for phosphatidylglycerol lipids put to a structural test}, journal = {J. Phys. Chem. B}, volume = {113}, number = {19}, year = {2009}, pages = {6958{\textendash}6963}, publisher = {Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, USA. jhenin@cmm.chem.upenn.edu}, abstract = {Three atomistic empirical models for phosphatidylglycerol (PG) lipids are tested against structural data in the crystal and liquid crystal states. Simulations of the anhydrous crystal of dimyristoyl-phosphatidylglycerol (DMPG) show that only the CHARMM force field describes the conformation and interactions of PG head groups accurately. The other two models do not reproduce the native network of hydrogen bonds, suggesting the presence of biases in their conformational and nonbonded interaction properties. The CHARMM model is further validated in the biologically relevant liquid crystal phase by comparing experimental small-angle X-ray scattering spectra from DMPG unilamellar vesicles with data calculated from fluid bilayer simulations. The good agreement found in this model-free comparison implies that liquid crystal PG bilayers as described by CHARMM exhibit realistic bilayer thickness and lateral packing. Last, this model is used to simulate a fluid bilayer of palmitoyl-oleoyl-phosphatidylglycerol (POPG). The resulting view of the POPG bilayer structure is at variance with that proposed previously based on simulations, in particular, with respect to lateral packing of head groups and the role of counterions.}, keywords = {chemistry, Crystallography, Lipid Bilayers, Models, Molecular, Phosphatidylglycerols, Scattering, Small Angle, Water, X-Ray}, doi = {10.1021/jp900645z}, author = {J{\'e}r{\^o}me H{\'e}nin and Wataru Shinoda and Michael L Klein} } @article {2009|1942, title = {PEP-FOLD: an online resource for de novo peptide structure prediction.}, journal = {Nucleic Acids Res.}, volume = {37}, number = {Web Server issue}, year = {2009}, month = {jul}, pages = {W498{\textendash}W503}, keywords = {Algorithms, Internet, Models, Molecular, Peptides, Protein, Protein Conformation, Reproducibility of Results, Sequence Analysis, Software, User-Computer Interface}, doi = {10.1093/nar/gkp323}, author = {Julien Maupetit and Philippe Derreumaux and Pierre Tuffery} } @article {2009|2009, title = {Structural diversity of the soluble trimers of the human amylin(20-29) peptide revealed by molecular dynamics simulations}, journal = {J. Chem. Phys.}, volume = {130}, number = {12}, year = {2009}, month = {mar}, pages = {125101}, keywords = {Amino Acid Sequence, Amyloid, Humans, Models, Molecular, Molecular Sequence Data, Peptide Fragments, Protein Multimerization, Protein Structure, Quaternary, Solubility, Solvents}, doi = {10.1063/1.3097982}, author = {Mo, Yuxiang and Lu, Yan and Wei, Guanghong and Philippe Derreumaux} } @article {2009|2019, title = {Thermodynamics and dynamics of amyloid peptide oligomerization are sequence dependent}, journal = {Proteins: Struct., Funct., Bioinf.}, volume = {75}, number = {4}, year = {2009}, month = {jun}, pages = {954{\textendash}963}, keywords = {Amino Acid Sequence, Amyloid beta-Protein, beta 2-Microglobulin, Cluster Analysis, Computer Simulation, Models, Molecular, Peptide Fragments, Protein Multimerization, Protein Structure, Secondary, Structure-Activity Relationship, Thermodynamics}, doi = {10.1002/prot.22305}, author = {Lu, Yan and Philippe Derreumaux and Guo, Zhi and Mousseau, Normand and Wei, Guanghong} } @article {2008|1603, title = {Diffusion of glycerol through Escherichia coli aquaglyceroporin GlpF}, journal = {Biophys. J.}, volume = {94}, number = {3}, year = {2008}, pages = {832{\textendash}839}, abstract = {The glycerol uptake facilitator, GlpF, a major intrinsic protein found in Escherichia coli, selectively conducts water and glycerol across the inner membrane. The free energy landscape characterizing the assisted transport of glycerol by this homotetrameric aquaglyceroporin has been explored by means of equilibrium molecular dynamics over a timescale spanning 0.12 micros. To overcome the free energy barriers of the conduction pathway, an adaptive biasing force is applied to the glycerol molecule confined in each of the four channels. The results illuminate the critical role played by intramolecular relaxation on the diffusion properties of the permeant. These free energy calculations reveal that glycerol tumbles and isomerizes on a timescale comparable to that spanned by its adaptive-biasing-force-assisted conduction in GlpF. As a result, reorientation and conformational equilibrium of glycerol in GlpF constitute a bottleneck in the molecular simulations of the permeation event. A profile characterizing the position-dependent diffusion of the permeant has been determined, allowing reaction rate theory to be applied for investigating conduction kinetics based on the measured free energy landscape.}, keywords = {Aquaporins, Chemical, Computer Simulation, Diffusion, Escherichia coli Proteins, Glycerol, Ion Channel Gating, Models, Molecular, Molecular Conformation, Porosity}, doi = {10.1529/biophysj.107.115105}, author = {J{\'e}r{\^o}me H{\'e}nin and Emad Tajkhorshid and Klaus Schulten and Christophe Chipot} } @article {1995|1941, title = {Solution structure of oligonucleotides covalently linked to a psoralen derivative.}, journal = {Nucleic Acids Res.}, volume = {23}, number = {5}, year = {1995}, month = {mar}, pages = {788{\textendash}795}, abstract = {

Psoralen (pso) was attached via its C-5 position to the 5\&$\#$39;-phosphate group of an oligodeoxynucleotide d(TAAGCCG) by a hexamethylene linker (m6). Complex formation between pso-m6-d(TAAGCCG) and the complementary strands d(CGGCTTA)[7-7mer] or d(CGGCTTAT)[7-8mer] was investigated by nuclear magnetic resonance in aqueous solution. Structural informations derived from DQF-COSY and NOESY maps, revealed that the mini double helix adopts a B-form conformation and that the deoxyriboses preferentially adopt a C2\&$\#$39;-endo conformation. The nOe connectivities observed between the protons of the bases or the sugars in each duplex, and the protons of the psoralen and the hexamethylene chain, led us to propose a model involving an equilibrium between two conformations due to different locations of the psoralen. Upon UV-irradiation, the psoralen moiety cross-linked the two DNA strands at the level of 5\&$\#$39;TpA3\&$\#$39; sequences. NMR studies of the single major photo-cross-linked duplex pso-m6-d(TAAGCCG) and d(CGGCTTA) were performed. The stereochemistry of the diadduct is indeed cis-syn at both cyclobutane rings. In addition, the effects of this diadduct on the helical structure are analyzed in detail.

}, keywords = {Base Sequence, chemistry, chemistry/radiation effects, Magnetic Resonance Spectroscopy, Models, Molecular, Molecular Sequence Data, Nucleic Acid Conformation, Oligodeoxyribonucleotides, Psoralens, Solutions}, author = {O. Bornet and Chantal Pr{\'e}vost and F. Vovelle and M. Chassignol and N. T. Thuong and G. Lancelot} } @article {1994|1968, title = {Three-dimensional structure of extended chromatin fibers as revealed by tapping-mode scanning force microscopy}, journal = {Proc. Natl. Acad. Sci. U.s.a.}, volume = {91}, number = {24}, year = {1994}, month = {nov}, pages = {11621{\textendash}11625}, abstract = {Unfixed chicken erythrocyte chromatin fibers in very low salt have been imaged with a scanning force microscope operating in the tapping mode in air at ambient humidity. These images reveal a three-dimensional organization of the fibers. The planar "zig-zag" conformation is rare, and extended "beads-on-a-string" fibers are seen only in chromatin depleted of histones H1 and H5. Glutaraldehyde fixation reveals very similar structures. Fibers fixed in 10 mM salt appear somewhat more compacted. These results, when compared with modeling studies, suggest that chromatin fibers may exist as irregular three-dimensional arrays of nucleosomes even at low ionic strength.}, keywords = {Animals, Atomic Force, Biological, Chickens, Chromatin, Fixatives, Histones, Microscopy, Models, Non-P.H.S., Non-U.S. Gov{\textquoteright}t, Osmolar Concentration, P.H.S., Research Support, Sodium Chloride, U.S. Gov{\textquoteright}t}, author = {S. H. Leuba and G. Yang and C. Robert and B. Samori and K. van Holde and J. Zlatanova and C. Bustamante} }