Download MendeleyProtein Regulation of Carotenoid Binding: Gatekeeper and Locking Amino Acid Residues in Reaction Centers of Rhodobacter sphaeroides
Roszak, A.W., McKendrick, K., Gardiner, A.T., Mitchell, I.A., Isaacs, N.W., Cogdell, R.J., Hashimoto, H., Frank, H.A.(2004) Structure 12: 765-773
- PubMed: 15130469 Search on PubMed
- DOI: https://doi.org/10.1016/j.str.2004.02.037
- Primary Citation Related Structures:
1RG5, 1RGN, 1RQK - PubMed Abstract:
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.
- Department of Chemistry, IBLS, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom.
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