Structural elements regulating the photochromicity in a cyanobacteriochrome.

ABSTRACT: The three-dimensional (3D) crystal structures of the GAF3 domain of cyanobacteriochrome Slr1393 (Synechocystis PCC6803) carrying a phycocyanobilin chromophore could be solved in both 15-Z dark-adapted state, Pr, λ_max = 649 nm, and 15-E photoproduct, Pg, λ_max = 536 nm (resolution, 1.6 and 1.86 Å, respectively). The structural data allowed identifying the large spectral shift of the Pr-to-Pg conversion as resulting from an out-of-plane rotation of the chromophore's peripheral rings and an outward movement of a short helix formed from a formerly unstructured loop. In addition, a third structure (2.1-Å resolution) starting from the photoproduct crystals allowed identification of elements that regulate the absorption maxima. In this peculiar form, gene

SUBMITTER: Xu X 

PROVIDER: S-EPMC7007540 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature