Identification of intermediate conformations in the photocycle of the light-driven sodium-pumping rhodopsin KR2.

ABSTRACT: The light-driven rhodopsin KR2 transports Na⁺via the M- and O-states. However, the mechanisms by which the retinal regulates Na⁺ pumping is unknown, in part because KR2 adopts both pentamer and monomer forms in crystal structures and in part because these structures show differences in the protein conformation near the Schiff base, even when they are of the same intermediate state within the photocycle. A particular open question is the nature of the H-bond networks and protonation state in the active site, including Asp116. Here, we analyze the protonation state and the absorption wavelength for each crystal structure, using a quantum mechanical/molecular mechanical approach. In the pentamer ground state, the calculated absorption wavelength reproduces the experiment

SUBMITTER: Tsujimura M 

PROVIDER: S-EPMC8039564 | biostudies-literature | 2021 Jan-Jun

REPOSITORIES: biostudies-literature