The Photocycle of Bacteriophytochrome Is Initiated by Counterclockwise Chromophore Isomerization.

ABSTRACT: Photoactivation of bacteriophytochrome involves a cis-trans photoisomerization of a biliverdin chromophore, but neither the precise sequence of events nor the direction of the isomerization is known. Here, we used nonadiabatic molecular dynamics simulations on the photosensory protein dimer to resolve the isomerization mechanism in atomic detail. In our simulations the photoisomerization of the D ring occurs in the counterclockwise direction. On a subpicosecond time scale, the photoexcited chromophore adopts a short-lived intermediate with a highly twisted configuration stabilized by an extended hydrogen-bonding network. Within tens of picoseconds, these hydrogen bonds break, allowing the chromophore to adopt a more planar configuration, which we assign to the early Lumi-R state. The isome

SUBMITTER: Morozov D 

PROVIDER: S-EPMC9150100 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature