4GLQ

Crystal Structure of the blue-light absorbing form of the Thermosynechococcus elongatus PixJ GAF-domain

Summary for 4GLQ

• Entry DOI: 10.2210/pdb4glq/pdb
• Related: 4FOF
• Descriptor: Methyl-accepting chemotaxis protein, Phycoviolobilin, blue light-absorbing form (3 entities in total)
• Functional Keywords: chromophore, phytochrome, cyanobacteriochrome, phycoviolobilin, bilin, bili-protein, cation-pi interaction, signaling protein, gaf domain, photoreceptor, phycoviolobilin adduct
• Biological source: Thermosynechococcus elongatus
• Total number of polymer chains: 1
• Total formula weight: 20188.90

Authors

Burgie, E.S.,Walker, J.M.,Phillips Jr., G.N.,Vierstra, R.D. (deposition date: 2012-08-14, release date: 2013-01-16, Last modification date: 2024-10-30)

Primary citation

Burgie, E.S.,Walker, J.M.,Phillips Jr., G.N.,Vierstra, R.D.
A Photo-Labile Thioether Linkage to Phycoviolobilin Provides the Foundation for the Blue/Green Photocycles in DXCF-Cyanobacteriochromes.
Structure, 21:88-97, 2013

PubMed Abstract: The phytochrome superfamily encompasses a diverse collection of photochromic photoreceptors in plants and microorganisms that employ a covalently linked bilin cradled in a cGMP-phosphodiesterase/adenylyl-cyclase/FhlA (GAF) domain to detect light. Whereas most interconvert between red- and far-red-light-absorbing states, cyanobacteria also express variants called cyanobacteriochromes (CBCRs) that modify bilin absorption to collectively perceive the entire visible spectrum. Here, we present two X-ray crystallographic structures of the GAF domain from the blue/green photochromic CBCR PixJ from Thermosynechococcus elongatus. These structures confirm the hypothesis that CBCRs variably manipulate the chromophore π-conjugation system through isomerization and a second thioether linkage, in this case involving the bilin C10 carbon and Cys494 within a DXCF sequence characteristic of blue/green CBCRs. Biochemical studies support a mechanism for photoconversion whereby the second linkage ruptures on route to the green-light-absorbing state. Collectively, the TePixJ(GAF) models illustrate the remarkable structural and photochemical versatility among phytochromes and CBCRs in driving light perception.

PubMed: 23219880
DOI: 10.1016/j.str.2012.11.001

Experimental method

X-RAY DIFFRACTION (1.772 Å)