Photocycle-dependent conformational changes in the proteorhodopsin cross-protomer Asp-His-Trp triad revealed by DNP-enhanced MAS-NMR.

ABSTRACT: Proteorhodopsin (PR) is a highly abundant, pentameric, light-driven proton pump. Proton transfer is linked to a canonical photocycle typical for microbial ion pumps. Although the PR monomer is able to undergo a full photocycle, the question arises whether the pentameric complex formed in the membrane via specific cross-protomer interactions plays a role in its functional mechanism. Here, we use dynamic nuclear polarization (DNP)-enhanced solid-state magic-angle spinning (MAS) NMR in combination with light-induced cryotrapping of photointermediates to address this topic. The highly conserved residue H75 is located at the protomer interface. We show that it switches from the (τ)- to the (π)-tautomer and changes its ring orientation in the M state. It couples to W34 across the oligomerization

SUBMITTER: Maciejko J 

PROVIDER: S-EPMC6486740 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature