Light-induced complex formation of bacteriophytochrome RpBphP1 and gene repressor RpPpsR2 probed by SAXS

Papiz, Miroslav Z ORCID: 0000-0001-6720-8349, Bellini, Dom, Evans, Kate, Grossmann, Gunter and Fordham-Skelton, Tony (2019) Light-induced complex formation of bacteriophytochrome RpBphP1 and gene repressor RpPpsR2 probed by SAXS. FEBS JOURNAL, 286 (21). pp. 4261-4277.

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Official URL: http://dx.doi.org/10.1111/febs.14973

Abstract

Bacteriophytochrome proteins (BphPs) are molecular light switches that enable organisms to adapt to changing light conditions through the control of gene expression. Canonical type 1 BphPs have histidine kinase output domains, but type 3 RpBphP1, in the bacterium Rhodopseudomonas palustris (Rps. palustris), has a C terminal PAS9 domain and a two-helix output sensor (HOS) domain. Type 1 BphPs form head-to-head parallel dimers; however, the crystal structure of RpBphP1ΔHOS, which does not contain the HOS domain, revealed pseudo anti-parallel dimers. HOS domains are homologs of Dhp dimerization domains in type 1 BphPs. We show, by applying the small angle X-ray scattering (SAXS) technique on full-length RpBphP1, that HOS domains fulfill a similar role in the formation of parallel dimers. On illumination with far-red light, RpBphP1 forms a complex with gene repressor RpPpsR2 through light-induced structural changes in its HOS domains. An RpBphP1:RpPpsR2 complex is formed in the molecular ratio of 2 : 1 such that one RpBphP1 dimer binds one RpPpsR2 monomer. Molecular dimers have been modeled with Pfr and Pr SAXS data, suggesting that, in the Pfr state, stable dimeric four α-helix bundles are formed between HOS domains, rendering RpBphP1functionally inert. On illumination with light of 760 nm wavelength, four α-helix bundles formed by HOS dimers are disrupted, rendering helices available for binding with RpPpsR2.

Item Type:	Article
Uncontrolled Keywords:	bacteriophytochrome, complex formation, photo-induced changes, photosynthesis, SAXS
Depositing User:	Symplectic Admin
Date Deposited:	16 Jul 2019 14:42
Last Modified:	15 Oct 2023 11:37
DOI:	10.1111/febs.14973
Open Access URL:	https://doi.org/10.1111/febs.14973
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3050047