1rg5
From Proteopedia
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Structure of the photosynthetic reaction centre from Rhodobacter sphaeroides carotenoidless strain R-26.1
Overview
X-ray diffraction was used to determine high-resolution structures of the reaction center (RC) complex from the carotenoidless mutant, Rb. sphaeroides R-26.1, without or reconstituted with carotenoids. The results are compared with the structure of the RC from a semiaerobically grown Rb. sphaeroides strain 2.4.1. The investigation reveals the structure of the carotenoid in the different protein preparations, the nature of its binding site, and a plausible mechanism by which the carotenoid is incorporated unidirectionally in its characteristic geometric configuration. The structural data suggest that the accessibility of the carotenoid to the binding site is controlled by a specific "gatekeeper" residue which allows the carotenoid to approach the binding site from only one direction. Carotenoid binding to the protein is secured by hydrogen bonding to a separate "locking" amino acid. The study reveals the specific molecular interactions that control how the carotenoid protects the photosynthetic apparatus against photo-induced oxidative destruction.
About this Structure
1RG5 is a Protein complex structure of sequences from Rhodobacter sphaeroides with , , , , , and as ligands. Full crystallographic information is available from OCA.
Reference
Protein regulation of carotenoid binding; gatekeeper and locking amino acid residues in reaction centers of Rhodobacter sphaeroides., Roszak AW, McKendrick K, Gardiner AT, Mitchell IA, Isaacs NW, Cogdell RJ, Hashimoto H, Frank HA, Structure. 2004 May;12(5):765-73. PMID:15130469
Page seeded by OCA on Thu Feb 21 14:50:39 2008
