Aerobic regulation of isocitrate dehydrogenase gene (icd) expression in Escherichia coli by the arcA and fnr gene products

Garlo Chao, Joan Shen, Ching-Ping Tseng, Soon Jung Park, Robert P. Gunsalus*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Isocitrate dehydrogenase, the icd gene product, has been studied extensively regarding the regulation of enzymatic activity and its relationship to the metabolic flux between the tricarboxylic acid cycle and the glyoxylate bypass. In this study, the transcriptional regulation of icd gene expression was monitored by using an icd-lacZ gene fusion and shown to vary over a 15-fold range in response to changes in oxygen and carbon availability. Anaerobic cell growth resulted in fivefold-lower icd-lacZ expression than during aerobic growth. This negative control is mediated by the orcA and fnr gene products. When different carbon compounds were used for cell growth, icd-lacZ expression varied threefold. The results of continuous cell culture studies indicated that this control may be due to variations in cell growth rate rather than to catabolite repression. DNase I footprinting at the icd promoter revealed a 42-bp ArcA-phosphate-protected region that overlaps the start site of icd transcription. Phosphorylation of ArcA considerably enhanced its binding to DNA, while ArcA-phosphate exhibited an apparent dissociation value of approximately 0.1 μM. Based on these studies, ArcA appears to function as a classical repressor of transcription by binding at a site overlapping the icd promoter during anaerobic cell growth conditions.

Original languageEnglish
Pages (from-to)4299-4304
Number of pages6
JournalJournal of Bacteriology
Volume179
Issue number13
DOIs
StatePublished - Jul 1997

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