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Structural basis for the Pr-Pfr long-range signaling mechanism of a full-length bacterial phytochrome at the atomic level

ABSTRACT: Light sensing mechanisms allow prokaryotes and eukaryotes to adapt to constantly changing environmental factors. Phytochromes constitute a widespread biological photoreceptor family that typically interconvert between two photostates called Pr (red light-absorbing) and Pfr (far-red light-absorbing). Despite the vast structural information reported on phytochromes, the lack of full-length structures solved at the (near-)atomic level in both pure Pr and Pfr states leaves gaps in the structural mechanisms involved in the signal transmission pathways during the photoconversion. Here we present the crystallographic structures of three versions from the plant pathogen Xanthomonas campestris virulence regulator XccBphP bacteriophytochrome, including two full-length proteins, in the Pr and Pfr states. The structures show a reorganization of the interaction networks within and around the chromophore-binding pocket, an α-helix/β-sheet tongue transition, specific domain reorientations, along with interchanging kinks and breaks at the helical spine as a result of the photoswitching, which subsequently affect the quaternary assembly of the protein. These structural findings, combined with mutational, biochemical and computational studies, allow us to describe the signaling mechanism of a full-length bacterial phytochrome at the atomic level. As the transduction mechanism herein reported involves elements highly conserved in other phytochromes, it might be extended to other members of this family of photoreceptors.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Xanthomonas Campestris

SUBMITTER: Germán Rosano

LAB HEAD: Germán Rosano

PROVIDER: PXD026829 | Pride | 2021-12-17

REPOSITORIES: Pride

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			Action	DRS
	BphP_database.fasta	Fasta
	BphP_dimer_DSP-specId.ms2	Other
	BphP_dimer_DSP.mzid.gz	Mzid
	BphP_dimer_DSP.raw	Raw
	BphP_dimer_DSP_ionexclusion-specId.ms2	Other

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Structural basis for the Pr-Pfr long-range signaling mechanism of a full-length bacterial phytochrome at the atomic level

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