The Laboratoire International Associé between the Centre National de la Recherche Scientifique and the University of Illinois at Urbana-Champaign was launched at the end of 2012. Its primary objective is to develop methods for high-performance molecular simulation with the aim of understanding the function of complex biological assemblies, transcending the frontiers of traditional disciplines by uniting mathematicians, physicists, theoretical chemists and biologists on both sides of the Atlantic. In France, the major contributors are located at the Université de Lorraine, the École des Ponts ParisTech, the Institut de Biologie et Chimie des Protéines-Université Claude Bernard and the Laboratoire d'Ingénierie des Systèmes Macromoléculaires-Université d'Aix-Marseille. In the United States, the contributors belong to the NIH Resource for Macromolecular Modeling and Bioinformatics. In Nancy, the partner is a theoretical chemistry and biophysics group incepted in 2003. Its expertise lies in describing the structure and the dynamic properties of the biological membrane and elucidating the mechanisms of the cell machinery. To attain this goal, its members leverage numerical simulations over size and timescales commensurate with the biological process at hand. Over the years, the team has gleaned milestone results in such diverse research areas as membrane transport, interaction with the biological membrane, membrane protein structure and function, as well as self-organized molecular systems. They also develop original approaches in the field of free-energy calculations, as well as that of intermolecular potentials.
High-speed atomic force microscopy shows that annexin V stabilizes membranes on the second timescale. Annexins are abundant cytoplasmic proteins that can bind to negatively charged phospholipids in a Ca2+-dependent manner, and are known to play a role in the storage of Ca2+ and membrane healing. Little is known, however, about the dynamic processes of protein– Ca2+–membrane assembly and disassembly. Here we show that high-speed atomic force microscopy (HS-AFM) can be used to repeatedly induce and disrupt annexin assemblies and study their structure, dynamics and interactions. Our HS-AFM set-up is adapted for such biological applications through the integration of a pumping system for buffer exchange and a pulsed laser system for uncaging caged compounds. We find that biochemically identical annexins (annexin V) display different effective Ca2+ and membrane affinities depending on the assembly location, providing a wide Ca2+ buffering regime while maintaining membrane stabilization. We also show that annexin is membrane-recruited and forms stable supramolecular assemblies within ∼5 s in conditions that are comparable to a membrane lesion in a cell. Molecular dynamics simulations provide atomic detail of the role played by Ca2+ in the reversible binding of annexin to the membrane surface. Nature Nanotechnology, 2016.
High-speed atomic force microscopy shows that annexin V stabilizes membranes on the second timescale
2016, (), .
Ramadoss, V.; Dehez, F.; Chipot, C
AlaScan: A graphical user interface for alanine scanning free–energy calculations.
J. Chem. Info. Model.
2016, (56), 1122-1126.
Lee, C. T.; Comer, J.; Herndon, C.; Leung, N.; Pavlova, A.; Swift, R. V.; Tung, C.; Rowley, C. N.; Amaro, R. E.; Chipot, C.; Wang, Y.; Gumbart, J. C.
Simulation-Based Approaches for Determining Membrane Permeability of Small Compounds.
J. Chem. Inf. Model.
2016, (56), 721-733.
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