Site-Directed Mutagenesis of Rhodobacter sphaeroides Reaction Center: The Role of Tyrosine L222
Reaction centers (RCs) from purple photosynthetic bacteria have been used as a model system for the study of herbicides which act as competitive inhibitors of the secondary quinone, QB, of the acceptor quinone complex (1). The x-ray structures of RCs for Rps. viridis (2) and Rb. sphaeroides (3) have revealed some details of the QB/herbicide binding domain, as well as features of the interaction. Many herbicide resistant mutants have been isolated by various groups by selecting cells that grow in the presence of herbicide (4,5). However, it is now possible to learn more about the structure/function relationships of the RC by selectively altering any amino acid in the QB binding domain through site-directed mutagenesis. Here, we report the construction of a RC deletion mutant of Rb. sphaeroides which can be complemented by mutant RC genes to produce mutant RC proteins. Preliminary characterization of a site-directed mutant at Tyr L222 in the QB binding domain of the RC is also presented.
KeywordsDeletion Mutant Purple Photosynthetic Bacterium Secondary Quinone Photosynthetic Growth Reaction Center Preparation
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- 1.Wraight, CA. (1981) Israel J. Chem. 21,348–354.Google Scholar
- 10.Kunkle, TA. (1987) in Current protocols in molecular biology (Ausubel, F.M. et al. eds.) pp. 8.8.1.–8.8.6. John Wiley and Sons, New York.Google Scholar
- 11.Ditta, G., Schmidhauser, T., Yakobson, E., Lu, P., Iiang, X-W., Finlay, D.R., Guiney, D. and Helinski, D.R. (1985) 13,149–153.Google Scholar
- 14.Paddock, M.L., Rongey, S.H., Feher, G., and Okamura, M.Y. (1989) Proc. Acad. Sci. USA, in press.Google Scholar