@article {2023|2164, title = {Molecular determinants of inhibition of UCP1-mediated respiratory uncoupling.}, journal = {Nat Commun}, volume = {14}, year = {2023}, month = {2023 May 05}, pages = {2594}, abstract = {

Brown adipose tissue expresses uncoupling protein 1 (UCP1), which dissipates energy as heat, making it a target for treating metabolic disorders. Here, we investigate how purine nucleotides inhibit respiration uncoupling by UCP1. Our molecular simulations predict that GDP and GTP bind UCP1 in the common substrate binding site in an upright orientation, where the base moiety interacts with conserved residues R92 and E191. We identify a triplet of uncharged residues, F88/I187/W281, forming hydrophobic contacts with nucleotides. In yeast spheroplast respiration assays, both I187A and W281A mutants increase the fatty acid-induced uncoupling activity of UCP1 and partially suppress the inhibition of UCP1 activity by nucleotides. The F88A/I187A/W281A triple mutant is overactivated by fatty acids even at high concentrations of purine nucleotides. In simulations, E191 and W281 interact with purine but not pyrimidine bases. These results provide a molecular understanding of the selective inhibition of UCP1 by purine nucleotides.

}, keywords = {Adipose Tissue, Brown, Fatty Acids, Ion Channels, Membrane Proteins, Mitochondrial Proteins, Purine Nucleotides, Saccharomyces cerevisiae, Uncoupling Protein 1}, issn = {2041-1723}, doi = {10.1038/s41467-023-38219-9}, author = {Gagelin, Antoine and Largeau, Corentin and Masscheleyn, Sandrine and Piel, Mathilde S and Calder{\'o}n-Mora, Daniel and Bouillaud, Fr{\'e}d{\'e}ric and J{\'e}r{\^o}me H{\'e}nin and Miroux, Bruno} } @article {2022|2153, title = {Multiscale Computational Study of the Conformation of the Full-Length Intrinsically Disordered Protein MeCP2.}, journal = {J Chem Inf Model}, volume = {62}, year = {2022}, month = {2022 02 28}, pages = {958-970}, abstract = {

The malfunction of the methyl-CpG binding protein 2 (MeCP2) is associated with the Rett syndrome, one of the most common causes of cognitive impairment in females. MeCP2 is an intrinsically disordered protein (IDP), making its experimental characterization a challenge. There is currently no structure available for the full-length MeCP2 in any of the databases, and only the structure of its MBD domain has been solved. We used this structure to build a full-length model of MeCP2 by completing the rest of the protein via ab initio modeling. Using a combination of all-atom and coarse-grained simulations, we characterized its structure and dynamics as well as the conformational space sampled by the ID and transcriptional repression domain (TRD) domains in the absence of the rest of the protein. The present work is the first computational study of the full-length protein. Two main conformations were sampled in the coarse-grained simulations: a globular structure similar to the one observed in the all-atom force field and a two-globule conformation. Our all-atom model is in good agreement with the available experimental data, predicting amino acid W104 to be buried, amino acids R111 and R133 to be solvent-accessible, and having a 4.1\% α-helix content, compared to the 4\% found experimentally. Finally, we compared the model predicted by AlphaFold to our Modeller model. The model was not stable in water and underwent further folding. Together, these simulations provide a detailed (if perhaps incomplete) conformational ensemble of the full-length MeCP2, which is compatible with experimental data and can be the basis of further studies, e.g., on mutants of the protein or its interactions with its biological partners.

}, issn = {1549-960X}, doi = {10.1021/acs.jcim.1c01354}, author = {Ch{\'a}vez-Garc{\'\i}a, Cecilia and J{\'e}r{\^o}me H{\'e}nin and Karttunen, Mikko} } @article {2021|2147, title = {Mechanistic Insights on Heme-to-Heme Transmembrane Electron Transfer Within NADPH Oxydases From Atomistic Simulations.}, journal = {Front Chem}, volume = {9}, year = {2021}, month = {2021}, pages = {650651}, abstract = {

NOX5 is a member of the NADPH oxidase family which is dedicated to the production of reactive oxygen species. The molecular mechanisms governing transmembrane electron transfer (ET) that permits to shuttle electrons over the biological membrane have remained elusive for a long time. Using computer simulations, we report conformational dynamics of NOX5 embedded within a realistic membrane environment. We assess the stability of the protein within the membrane and monitor the existence of cavities that could accommodate dioxygen molecules. We investigate the heme-to-heme electron transfer. We find a reaction free energy of a few tenths of eV (ca. -0.3 eV) and a reorganization free energy of around 1.1 eV (0.8 eV after including electrostatic induction corrections). The former indicates thermodynamically favorable ET, while the latter falls in the expected values for transmembrane inter-heme ET. We estimate the electronic coupling to fall in the range of the μeV. We identify electron tunneling pathways showing that not only the W378 residue is playing a central role, but also F348. Finally, we reveal the existence of two connected Obinding pockets near the outer heme with fast exchange between the two sites on the nanosecond timescale. We show that when the terminal heme is reduced, O binds closer to it, affording a more efficient tunneling pathway than when the terminal heme is oxidized, thereby providing an efficient mechanism to catalyze superoxide production in the final step. Overall, our study reveals some key molecular mechanisms permitting reactive oxygen species production by NOX5 and paves the road for further investigation of ET processes in the wide family of NADPH oxidases by computer simulations.

}, issn = {2296-2646}, doi = {10.3389/fchem.2021.650651}, author = {Wu, Xiaojing and J{\'e}r{\^o}me H{\'e}nin and Baciou, Laura and Marc Baaden and Cailliez, Fabien and de la Lande, Aur{\'e}lien} } @article {2017|2021, title = {A membrane-inserted structural model of the yeast mitofusin Fzo1}, journal = {Sci Rep}, volume = {7}, year = {2017}, month = {2017 Aug 31}, pages = {10217}, type = {Research Article}, abstract = {

Mitofusins are large transmembrane GTPases of the dynamin-related protein family, and are required for the tethering and fusion of mitochondrial outer membranes. Their full-length structures remain unknown, which is a limiting factor in the study of outer membrane fusion. We investigated the structure and dynamics of the yeast mitofusin Fzo1 through a hybrid computational and experimental approach, combining molecular modelling and all-atom molecular dynamics simulations in a lipid bilayer with site-directed mutagenesis and in vivo functional assays. The predicted architecture of Fzo1 improves upon the current domain annotation, with a precise description of the helical spans linked by flexible hinges, which are likely of functional significance. In vivo site-directed mutagenesis validates salient aspects of this model, notably, the long-distance contacts and residues participating in hinges. GDP is predicted to interact with Fzo1 through the G1 and G4 motifs of the GTPase domain. The model reveals structural determinants critical for protein function, including regions that may be involved in GTPase domain-dependent rearrangements.

}, issn = {2045-2322}, doi = {10.1038/s41598-017-10687-2}, author = {De Vecchis, Dario and Cavellini, Laetitia and Marc Baaden and J{\'e}r{\^o}me H{\'e}nin and Cohen, Micka{\"e}l M and Antoine Taly} } @article {2015|1664, title = {Membrane Protein Structure, Function, and Dynamics: a Perspective from Experiments and Theory.}, journal = {J. Membr. Biol.}, volume = {248}, year = {2015}, publisher = {Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527, Athens, Greece, zcournia@bioacademy.gr.}, chapter = {611}, abstract = {

Membrane proteins mediate processes that are fundamental for the flourishing of biological cells. Membrane-embedded transporters move ions and larger solutes across membranes; receptors mediate communication between the cell and its environment and membrane-embedded enzymes catalyze chemical reactions. Understanding these mechanisms of action requires knowledge of how the proteins couple to their fluid, hydrated lipid membrane environment. We present here current studies in computational and experimental membrane protein biophysics, and show how they address outstanding challenges in understanding the complex environmental effects on the structure, function, and dynamics of membrane proteins.

}, doi = {10.1007/s00232-015-9802-0}, author = {Cournia, Zoe and Allen, Toby W. and Andricioaei, Ioan and Antonny, Bruno and Baum, Daniel and Grace Brannigan and Buchete, Nicolae-Viorel and Deckman, Jason T. and Delemotte, Lucie and Del Val, Coral and Friedman, Ran and Gkeka, Paraskevi and Hege, Hans-Christian and J{\'e}r{\^o}me H{\'e}nin and Kasimova, Marina A. and Kolocouris, Antonios and Michael L Klein and Khalid, Syma and Lemieux, M Joanne and Lindow, Norbert and Roy, Mahua and Selent, Jana and Mounir Tarek and Tofoleanu, Florentina and Vanni, Stefano and Urban, Sinisa and Wales, David J. and Smith, Jeremy C. and Bondar, Ana-Nicoleta} } @article {2010|1971, title = {Multiple binding sites for the general anesthetic isoflurane identified in the nicotinic acetylcholine receptor transmembrane domain.}, journal = {Proc. Natl. Acad. Sci. U.s.a.}, volume = {107}, number = {32}, year = {2010}, pages = {14122{\textendash}14127}, abstract = {An extensive search for isoflurane binding sites in the nicotinic acetylcholine receptor (nAChR) and the proton gated ion channel from Gloebacter violaceus (GLIC) has been carried out based on molecular dynamics (MD) simulations in fully hydrated lipid membrane environments. Isoflurane introduced into the aqueous phase readily partitions into the lipid membrane and the membrane-bound protein. Specifically, isoflurane binds persistently to three classes of sites in the nAChR transmembrane domain: (i) An isoflurane dimer occludes the pore, contacting residues identified by previous mutagenesis studies; analogous behavior is observed in GLIC. (ii) Several nAChR subunit interfaces are also occupied, in a site suggested by photoaffinity labeling and thought to positively modulate the receptor; these sites are not occupied in GLIC. (iii) Isoflurane binds to the subunit centers of both nAChR alpha chains and one of the GLIC chains, in a site that has had little experimental targeting. Interpreted in the context of existing structural and physiological data, the present MD results support a multisite model for the mechanism of receptor-channel modulation by anesthetics.}, doi = {10.1073/pnas.1008534107}, author = {Grace Brannigan and David N LeBard and J{\'e}r{\^o}me H{\'e}nin and Roderic G Eckenhoff and Michael L Klein} } @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} }