3zq5
From Proteopedia
Structure of the Y263F mutant of the cyanobacterial phytochrome Cph1
Structural highlights
FunctionPHY1_SYNY3 Regulatory photoreceptor which exists in two forms that are reversibly interconvertible by light: the R form that absorbs maximally in the red region of the spectrum and the FR form that absorbs maximally in the far-red region. Has also a slight blue shift for the far-red maximum. Forms a two-component system with the rcp1 response regulator. Publication Abstract from PubMedPhytochromes are biliprotein photoreceptors that can be photoswitched between red-light-absorbing state (Pr) and far-red-light-absorbing state (Pfr). Although three-dimensional structures of both states have been reported, the photoconversion and intramolecular signaling mechanisms are still unclear. Here, we report UV-Vis absorbance, fluorescence and CD spectroscopy along with various photochemical parameters of the wild type and Y263F, Y263H and Y263S mutants of the Cph1 photosensory module, as well as a 2.0-A-resolution crystal structure of the Y263F mutant in its Pr ground state. Although Y263 is conserved, we show that the aromatic character but not the hydroxyl group of Y263 is important for Pfr formation. The crystal structure of the Y263F mutant (Protein Data Bank ID: 3ZQ5) reaffirms the ZZZssa chromophore configuration and provides a detailed picture of its binding pocket, particularly conformational heterogeneity around the chromophore. Comparison with other phytochrome structures reveals differences in the relative position of the PHY (phytochrome specific) domain and the interaction of the tongue with the extreme N-terminus. Our data support the notion that native phytochromes in their Pr state are structurally heterogeneous. Spectroscopy and a high-resolution crystal structure of Tyr263 mutants of cyanobacterial phytochrome Cph1.,Mailliet J, Psakis G, Feilke K, Sineshchekov V, Essen LO, Hughes J J Mol Biol. 2011 Oct 14;413(1):115-27. Epub 2011 Aug 23. PMID:21888915[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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