Essential role of Glu-C66 for menaquinol oxidation indicates transmembrane electrochemical potential generation by Wolinella succinogenes fumarate reductase.

ABSTRACT: Quinol:fumarate reductase (QFR) is a membrane protein complex that couples the reduction of fumarate to succinate to the oxidation of quinol to quinone, in a reaction opposite to that catalyzed by the related enzyme succinate:quinone reductase (succinate dehydrogenase). In the previously determined structure of QFR from Wolinella succinogenes, the site of fumarate reduction in the flavoprotein subunit A of the enzyme was identified, but the site of menaquinol oxidation was not. In the crystal structure, the acidic residue Glu-66 of the membrane spanning, diheme-containing subunit C lines a cavity that could be occupied by the substrate menaquinol. Here we describe that, after replacement of Glu-C66 with Gln by site-directed mutagenesis, the resulting mutant is unable to grow on fumarate an

SUBMITTER: Lancaster CR 

PROVIDER: S-EPMC27176 | biostudies-literature | 2000 Nov

REPOSITORIES: biostudies-literature