4GW9

Structure of a bacteriophytochrome and light-stimulated protomer swapping with a gene repressor

Replaces:  4EHO

Summary for 4GW9

• Entry DOI: 10.2210/pdb4gw9/pdb
• Related: 3c2w
• Descriptor: bacteriophytochrome, BILIVERDINE IX ALPHA (3 entities in total)
• Functional Keywords: photoreceptor, pas/pac sensor, bacteriopbhytochrome, bacteriophytochrome photosensory and c-terminal output transducing domains, signaling protein, gene repressor rpppsr2, photosensory core domain and pas/pac domain, light signaling, ppsr2
• Biological source: Rhodopseudomonas palustris
• Total number of polymer chains: 4
• Total formula weight: 294163.30

Authors

Bellini, D.,Papiz, M.Z. (deposition date: 2012-09-01, release date: 2012-09-26)

Primary citation

Bellini, D.,Papiz, M.Z.
Structure of a bacteriophytochrome and light-stimulated protomer swapping with a gene repressor.
Structure, 20:1436-1446, 2012

PubMed Abstract: Phytochromes are photoreceptors in phototropic organisms that respond to light conditions by changing interactions between a response regulator and DNA. Bacterial phytochromes (BphPs) comprise an input photosensory core domain (PCD) and an output transducing domain (OTD). We report the structure of a BphP containing both PCD and the majority of its OTD, and demonstrate interaction with its cognate repressor. The OTD of RpBphP1, from Rhodopseudomonas palustris, is composed of a PAS/PAC domain and, to our knowledge, a hitherto unrecognized two-helix output sensor (HOS) domain. Unlike canonical BphPs, it does not transmit phosphorelay signals but forms a complex with the transcriptional repressor RpPpsR2 on photoconversion with far-red light. We show that HOS is essential for complex formation and that the anti-parallel dimer geometry is crucial in achieving HOS domain activation and protomer swapping under the control of light. These results provide insights into the steps taken by a two-component signaling system.

PubMed: 22795083

Experimental method

X-RAY DIFFRACTION (2.9 Å)