2phy
From Proteopedia
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PHOTOACTIVE YELLOW PROTEIN, DARK STATE (UNBLEACHED)
Overview
A photosensing protein directs light energy captured by its chromophore, into a photocycle. The protein's structure must accommodate the photocycle, and promote the resulting chemical or conformational changes that lead to, signal transduction. The 1.4 A crystallographic structure of photoactive, yellow protein, determined by multiple isomorphous replacement methods, provides the first view at atomic resolution of a protein with a, photocycle. The alpha/beta fold, which differs from the original chain, tracing, shows striking similarity to distinct parts of the signal, transduction proteins profilin and the SH2 domain. In the dark state, structure of photoactive yellow protein, the novel 4-hydroxycinnamyl, chromophore, covalently attached to Cys69, is buried within the major, hydrophobic core of the protein and is tethered at both ends by hydrogen, bonds. In the active site, the yellow anionic form of the chromophore is, stabilized by hydrogen bonds from the side chains of Tyr42 and buried, Glu46 to the phenolic oxygen atom and by electrostatic complementarity, with the positively charged guanidinium group of Arg52. Thr50 further, interlocks Tyr42, Glu46, and Arg52 through a network of active site, hydrogen bonds. Arg52, located in a concavity of the protein surface, adjacent to the dominant patch of negative electrostatic potential, shields the chromophore from solvent and is positioned to form a gateway, for the phototactic signal. Overall, the high-resolution structure of, photoactive yellow protein supports a mechanism whereby electrostatic, interactions create an active site poised for photon-induced, rearrangements and efficient protein-mediated signal transduction.
About this Structure
2PHY is a Single protein structure of sequence from Halorhodospira halophila with HC4 as ligand. This structure superseeds the now removed PDB entry 1PHY. Full crystallographic information is available from OCA.
Reference
1.4 A structure of photoactive yellow protein, a cytosolic photoreceptor: unusual fold, active site, and chromophore., Borgstahl GE, Williams DR, Getzoff ED, Biochemistry. 1995 May 16;34(19):6278-87. PMID:7756254
Page seeded by OCA on Wed Nov 21 13:32:28 2007
