Supplementary Material for: Transcriptional Repressor HipB Regulates the Multiple Promoters in <b><i>Escherichia coli</i></b>

HipB is a DNA-binding protein in <i>Escherichia coli</i> and negatively regulates its own promoter by binding to the palindromic sequences [TATCCN<sub>8</sub>GGATA (N represents any nucleotides)] on the <i>hipBA</i> promoter. For such sequences, bioinformatic analysis revealed that there are a total of 39 palindromic sequences (TATCCN<sub>(x)</sub>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 <i>E. coli</i> genome. Notably, <i>eutH</i> and <i>fadH</i> have two and three TATCCN<sub>(x)</sub>GGATA palindromic sequences located in their promoters, respectively. Another significant finding was that a palindromic sequence was also identified in the promoter region of <i>hipAB</i> 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 <i>eutH</i>,<i> fadH</i>, as well as the <i>relA</i> promoter regions and represses their expressions. We further demonstrated that HipA enhances the repression of the <i>relA</i> promoter activity by HipB. This effect was not observed 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.