Protein 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. and Frank, H.A. (2004) Protein regulation of carotenoid binding: Gatekeeper and locking amino acid residues in reaction centers of Rhodobacter sphaeroides. Structure, 12, pp. 765-773. (doi:10.1016/j.str.2004.02.037)

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Publisher's URL: http://dx.doi.org/10.1016/j.str.2004.02.037

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.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Cogdell, Professor Richard and Isaacs, Professor Neil and Roszak, Dr Aleksander
Authors: Roszak, A.W., McKendrick, K., Gardiner, A.T., Mitchell, I.A., Isaacs, N.W., Cogdell, R.J., Hashimoto, H., and Frank, H.A.
College/School:College of Medical Veterinary and Life Sciences > Institute of Molecular Cell and Systems Biology
College of Science and Engineering > School of Chemistry
Journal Name:Structure
ISSN:0969-2126
ISSN (Online):1878-4186
Published Online:11 May 2004

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