K⁺ binding and proton redistribution in the E₂P state of the H⁺, K⁺-ATPase.

ABSTRACT: The H⁺, K⁺-ATPase (HKA) uses ATP to pump protons into the gastric lumen against a million-fold proton concentration gradient while counter-transporting K⁺ from the lumen. The mechanism of release of a proton into a highly acidic stomach environment, and the subsequent binding of a K⁺ ion necessitates a network of protonable residues and dynamically changing protonation states in the cation binding pocket dominated by five acidic amino acid residues E343, E795, E820, D824, and D942. We perform molecular dynamics simulations of spontaneous K⁺ binding to all possible protonation combinations of the acidic amino acids and carry out free energy calculations to determine the optimal protonation state of the luminal-open E₂P state

SUBMITTER: Dubey V 

PROVIDER: S-EPMC6109069 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature