ISSN:
1573-5079
Keywords:
electron transfer
;
herbicide binding
;
membrane protein
;
site-directed mutagenesis
;
ubiquinone binding
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Three single-site mutations have been introduced at positions close to the QA ubiquinone in the reaction centre from Rhodobacter sphaeroides. Two of these mutations, Ala M260 to Trp and Ala M248 to Trp, result in a reaction centre that does not support photosynthetic growth of the bacterium, and in which electron transfer to the QA ubiquinone is abolished. In the reaction centre with an Ala to Trp mutation at the M260 residue, electron transfer from the primary donor to the acceptor bacteriopheophytin is not affected by the mutation, but electron transfer from the acceptor bacteriopheophytin to QA is not observed. The most likely basis for these effects is that the mutation produces a structural change that excludes binding of the QA ubiquinone. A third mutation, Leu M215 to Trp, produces a reaction centre that has an impaired capacity for supporting photosynthetic growth. The mutation changes the nature of ubiquinone binding at the QA site, and renders the site sensitive to quinone site inhibitors such as o- phenanthroline. Adopting a similar approach, in which a small residue located close to a cofactor is changed to a more bulky residue, we show that the reaction centre can be rendered carotenoid-less by the mutation Gly M71 to Leu.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1006111321083
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