Isolation and Properties of Fumarate Reductase Mutants of Escherichia coli
AUTOR(ES)
Spencer, Margaret E.
RESUMO
Escherichia coli produces two enzymes which interconvert succinate and fumarate: succinate dehydrogenase, which is adapted to an oxidative role in the tricarboxylic acid cycle, and fumarate reductase, which catalyzes the reductive reaction more effectively and allows fumarate to function as an electron acceptor in anaerobic growth. A glycerol plus fumarate medium was devised for the selection of mutants (frd) lacking a functional fumarate reductase by virtue of their inability to use fumarate as an anaerobic electron acceptor. Most of the mutants isolated contained less than 1% of the parental fumarate reduction activity. Measurements of the fumarate reduction and succinate oxidation activities of parental strains and frd mutants after aerobic and anaerobic growth indicated that succinate dehydrogenase was completely repressed under anaerobic conditions, the assayable succinate oxidation activity being due to fumarate reductase acting reversibly. Fumarate reductase was almost completely repressed under aerobic conditions, although glucose relieved this repression to some extent. The mutations, presumably in the structural gene (frd) for fumarate reductase, were located at approximately 82 min on the E. coli chromosome by conjugation and transduction with phage P1. frd is very close to the ampA locus, and the order of markers in this region was established as ampA-frd-purA.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=251810Documentos Relacionados
- Three classes of Escherichia coli mutants selected for aerobic expression of fumarate reductase.
- Molybdenum effector of fumarate reductase repression and nitrate reductase induction in Escherichia coli.
- Improved conversion of fumarate to succinate by Escherichia coli strains amplified for fumarate reductase.
- Identification of membrane anchor polypeptides of Escherichia coli fumarate reductase.
- Structure of fumarate reductase on the cytoplasmic membrane of Escherichia coli.