The RpoS-mediated regulation of isocitrate dehydrogenase gene expression in Escherichia coli.
The Escherichia coli NADP(+)-dependent isocitrate dehydrogenase (IDH; EC 1.1.1.42), encoded by an icd gene, is a tricarboxylic acid (TCA) cycle enzyme responsible for the oxidative decarboxylation of isocitrate to alpha-ketoglutarate. In order to examine how the icd gene expression is regulated, an icd-lacZ reporter fusion was constructed. While the icd gene was induced in exponential growth phase, it was repressed in stationary growth phase. Genetic inactivation of an rpoS gene, whose product is an alternative sigma factor, induced the icd gene expression approximately 4.8 times more in the stationary phase and the IDH enzyme activity in the rpoS mutant was 3.2 times higher than that in the wild type, indicating that the RpoS factor acts as a negative regulator of the icd gene expression in the stationary phase.
Jung
Ii Lae
IL
Department of Radiation Biology, Environmental Radiation Research Group, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Taejon 305-600, Korea.
Kim
Sung Keun
SK
Kim
In Gyu
IG
D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics* / Q000502:physiology; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D016254:Mutagenesis, Insertional; D012808:Sigma Factor / Q000502:physiology*; D001616:beta-Galactosidase / Q000032:analysis
D001426:Bacterial Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D007521:Isocitrate Dehydrogenase; D001616:beta-Galactosidase