An angular motion of a conserved four-helix bundle facilitates alternating access transport in the TtNapA and EcNhaA transporters.

ABSTRACT: There is ongoing debate regarding the mechanism through which cation/proton antiporters (CPAs), like Thermus thermophilus NapA (TtNapA) and Escherichia coli NapA (EcNhaA), alternate between their outward- and inward-facing conformations in the membrane. CPAs comprise two domains, and it is unclear whether the transition is driven by their rocking-bundle or elevator motion with respect to each other. Here we address this question using metadynamics simulations of TtNapA, where we bias conformational sampling along two axes characterizing the two proposed mechanisms: angular and translational motions, respectively. By applying the bias potential for the two axes simultaneously, as well as to the angular, but not the translational, axis alone, we manage to reproduce each of the two kno

SUBMITTER: Masrati G 

PROVIDER: S-EPMC7749304 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature