Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 104, Issue 30, Pages 12571-12576Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.0701737104
Keywords
biliverdin; red-light photoreceptor
Categories
Funding
- NIGMS NIH HHS [R37 GM036452, R01 GM036452, GM036452] Funding Source: Medline
Ask authors/readers for more resources
Bacteriophytochromes RpBphP2 and RpBphP3 from the photosynthetic bacterium Rhodopseudomonas palustris work in tandem to modulate synthesis of the light-harvesting complex LH4 in response to light. Although RpBphP2 and RpBphP3 share the same domain structure with 52% sequence identity, they demonstrate distinct photoconversion behaviors. RpBphP2 exhibits the classical phytochrome behavior of reversible photoconversion between red (Pr) and far-red (Pfr) light-absorbing states, whereas RpBphP3 exhibits novel photoconversion between Pr and a near-red (Pnr) light-absorbing states. We have determined the crystal structure at 2.2-angstrom resolution of the chromophore binding domains of RpBphP3, covalently bound with chromophore biliverdin IX alpha. By combining structural and sequence analyses with site-directed mutagenesis, we identify key residues that directly modulate the photochemical properties of RpBphP3 and RpBphP2. Remarkably, we identify a region spanning residues 207-212 in RpBphP3, in which a single mutation, L207Y, causes this unusual bacteriophytochrome to revert to the classical phenotype that undergoes reversible photoconversion between the Pr and Pfr states. The reverse mutation, Y193L, in the corresponding region in RpBphP2 significantly diminishes the formation of the Pfr state. We propose that residues 207-212 and the spatially adjacent conserved residues, Asp-216 and Tyr-272, interact with the chromophore and form part of the interface between the chromophore binding domains and the PHY domain that modulates photoconversion.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available