Transcriptional regulation of the fad regulon genes of Escherichia coli by ArcA

Abstract

ArcA is a global transcription factor required for optimal growth ofEscherichia coliduring anaerobic growth. In this study, the role of ArcA on the transcriptional regulatory subnetwork of thefadregulon was investigated. Gene expression profiles of deletion mutants (ΔarcA, ΔfadRand ΔarcA/ΔfadR) indicated that (i) ArcA is a major transcription factor for the transcriptional regulation of fatty acid metabolism in the absence of oxygen, and (ii) ArcA and FadR cooperatively regulate thefadregulon under anaerobic conditions. To determine the direct interaction between ArcA and the promoters of thefadregulon genes, chromatin immunoprecipitation (ChIP) analysis was performed. ChIP analysis suggested that ArcA directly binds to the promoter regions of thefadregulon genesin vivo. An ArcA-binding motif was identified from known binding sequences and predicted putative binding sites in the promoter regions of thefadregulon genes. These results indicate that ArcA directly represses the expression offadregulon genes during anaerobic growth.