Transcriptional Repressor HipB Regulates the Multiple Promoters in Escherichia coli

Abstract

HipB is a DNA-binding protein in Escherichia coli and negatively regulates its own promoter by binding to the palindromic sequences [ TATCC N 8 GGATA (N represents any nucleotides)] on the hipBA promoter. For such sequences, bioinformatic analysis revealed that there are a total of 39 palindromic sequences ( TATCC N (x) GGATA : N is any nucleotides and x is the number of nucleotides from 1 to 30) in the promoter regions of 33 genes on the E. coli genome. Notably, eutH and fadH have two and three TATCC N (x) GGATA palindromic sequences located in their promoters, respectively. Another significant finding was that a palindromic sequence was also identified in the promoter region of hipAB locus, known to be involved in the RelA-dependent persister cell formation in bacteria. Here, we demonstrated that HipB binds to the palindromic structures in the eutH , fadH , as well as the relA promoter regions and represses their expressions. We further demonstrated that HipA enhances the repression of the relA promoter activity by HipB. This effect was not ob-served with D291A HipA mutant which was previously shown to lack an ability to interact with HipB, indicating that HipA enhances the HipB's repressor activity through direct interaction with HipB. © 2013 S. Karger AG, Basel.