3pyp
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(New page: 200px<br /><applet load="3pyp" size="450" color="white" frame="true" align="right" spinBox="true" caption="3pyp, resolution 0.85Å" /> '''PHOTOACTIVE YELLOW P...)
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Revision as of 17:50, 20 November 2007
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PHOTOACTIVE YELLOW PROTEIN, CRYOTRAPPED EARLY LIGHT CYCLE INTERMEDIATE
Overview
Protein photosensors from all kingdoms of life use bound organic, molecules, known as chromophores, to detect light. A specific double bond, within each chromophore is isomerized by light, triggering slower changes, in the protein as a whole. The initial movements of the chromophore, which, can occur in femtoseconds, are tightly constrained by the surrounding, protein, making it difficult to see how isomerization can occur, be, recognized, and be appropriately converted into a protein-wide structural, change and biological signal. Here we report how this dilemma is resolved, in the photoactive yellow protein (PYP). We trapped a key early, intermediate in the light cycle of PYP at temperatures below -100 degrees, C, and determined its structure at better than 1 A resolution. The, 4-hydroxycinnamoyl chromophore isomerizes by flipping its thioester, linkage with the protein, thus avoiding collisions resulting from, large-scale movement of its aromatic ring during the initial light, reaction. A protein-to-chromophore hydrogen bond that is present in both, the preceding dark state and the subsequent signalling state of the, photosensor breaks, forcing one of the hydrogen-bonding partners into a, hydrophobic pocket. The isomerized bond is distorted into a conformation, resembling that in the transition state. The resultant stored energy is, used to drive the PYP light cycle. These results suggest a model for, phototransduction, with implications for bacteriorhodopsin, photoactive, proteins, PAS domains, and signalling proteins.
About this Structure
3PYP is a Single protein structure of sequence from Halorhodospira halophila with HC4 as ligand. Full crystallographic information is available from OCA.
Reference
Structure at 0.85 A resolution of an early protein photocycle intermediate., Genick UK, Soltis SM, Kuhn P, Canestrelli IL, Getzoff ED, Nature. 1998 Mar 12;392(6672):206-9. PMID:9515969
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