4Q0H

Deinococcus radiodurans BphP PAS-GAF

Summary for 4Q0H

• Entry DOI: 10.2210/pdb4q0h/pdb
• Related: 4Q0I 4Q0J
• Descriptor: Bacteriophytochrome, CHLORIDE ION, ISOPROPYL ALCOHOL, ... (5 entities in total)
• Functional Keywords: pas gaf, photosensor, response regulator, transferase
• Biological source: Deinococcus radiodurans R1
• Total number of polymer chains: 1
• Total formula weight: 37825.66

Authors

Burgie, E.S.,Vierstra, R.D. (deposition date: 2014-04-02, release date: 2014-07-16, Last modification date: 2024-02-28)

Primary citation

Burgie, E.S.,Wang, T.,Bussell, A.N.,Walker, J.M.,Li, H.,Vierstra, R.D.
Crystallographic and Electron Microscopic Analyses of a Bacterial Phytochrome Reveal Local and Global Rearrangements during Photoconversion.
J.Biol.Chem., 289:24573-24587, 2014

PubMed Abstract: Phytochromes are multidomain photoswitches that drive light perception in plants and microorganisms by coupling photoreversible isomerization of their bilin chromophore to various signaling cascades. How changes in bilin conformation affect output by these photoreceptors remains poorly resolved and might include several species-specific routes. Here, we present detailed three-dimensional models of the photosensing module and a picture of an entire dimeric photoreceptor through structural analysis of the Deinococcus radiodurans phytochrome BphP assembled with biliverdin (BV). A 1.16-Å resolution crystal structure of the bilin-binding pocket in the dark-adapted red light-absorbing state illuminated the intricate network of bilin/protein/water interactions and confirmed the protonation and ZZZssa conformation of BV. Structural and spectroscopic comparisons with the photochemically compromised D207A mutant revealed that substitutions of Asp-207 allow inclusion of cyclic porphyrins in addition to BV. A crystal structure of the entire photosensing module showed a head-to-head, twisted dimeric arrangement with bowed helical spines and a hairpin protrusion connecting the cGMP phosphodiesterase/adenylyl cyclase/FhlA (GAF) and phytochrome-specific (PHY) domains. A key conserved hairpin feature is its anti-parallel, two β-strand stem, which we show by mutagenesis to be critical for BphP photochemistry. Comparisons of single particle electron microscopic images of the full-length BphP dimer in the red light-absorbing state and the photoactivated far-red light-absorbing state revealed a large scale reorientation of the PHY domain relative to the GAF domain, which alters the position of the downstream histidine kinase output module. Together, our data support a toggle model whereby bilin photoisomerization alters GAF/PHY domain interactions through conformational modification of the hairpin, which regulates signaling by impacting the relationship between sister output modules.

PubMed: 25006244
DOI: 10.1074/jbc.M114.571661

Experimental method

X-RAY DIFFRACTION (1.157 Å)