Coarse-Grain Simulations of the R-SNARE Fusion Protein in its Membrane Environment Detect Long-Lived Conformational Sub-States

Coarse-grain molecular dynamics are used to look at conformational and dynamic aspects of an R-SNARE peptide inserted in a lipid bilayer. This approach allows carrying out microsecond-scale simulations which bring to light long-lived conformational sub-states potentially interesting in the context of the membrane fusion mechanism mediated by the SNARE proteins. We show that these coarse-grain models are in agreement with most experimental data on the SNARE system, but differ in some details that may have a functional interest, most notably in the orientation of the soluble part of R-SNARE that does not appear to be spontaneously accessible for SNARE complex formation. We also compare rat and yeast sequences of R-SNARE and find some minor differences in their behavior.