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 Structurale and the Laboratoire de Biologie Physico-Chimique. 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 to tackle rare events in biology.
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Correlation of membrane protein conformational and functional dynamics. Conformational changes in ion channels lead to gating of an ion-conductive pore. Ion flux has been measured with high temporal resolution by single-channel electrophysiology for decades. However, correlation between functional and conformational dynamics remained difficult, lacking experimental techniques to monitor sub-millisecond conformational changes. Here, we use the outer membrane protein G (OmpG) as a model system where loop-6 opens and closes the β-barrel pore like a lid in a pH-dependent manner. Functionally, single-channel electrophysiology shows that while closed states are favored at acidic pH and open states are favored at physiological pH, both states coexist and rapidly interchange in all conditions. Using HS-AFM height spectroscopy (HS-AFM-HS), we monitor sub-millisecond loop-6 conformational dynamics, and compare them to the functional dynamics from single-channel recordings, while MD simulations provide atomistic details and energy landscapes of the pHdependent loop-6 fluctuations. HS-AFM-HS offers new opportunities to analyze conformational dynamics at timescales of domain and loop fluctuations. Nature Communications, 2021.
Recent publications
Free Energy Methods for the Description of Molecular Processes
Christophe Chipot;
Annual Review of Biophysics (2023) 52 (1):
A Practical Guide to Recent Advances in Multiscale Modeling and Simulation of BiomoleculesEnhanced Sampling Based on Collective Variables
Yong Wang; Ruhong Zhou; Haohao Fu; Wensheng Cai; Christophe Chipot; Xueguang Shao; (2023) 1-22
Chasing collective variables using temporal data-driven strategies
Haochuan Chen; Christophe Chipot;
QRB Discovery (2023) 413 (242-