Transcription Factor HusR (YnfL) Is a Novel Regulator for Hydroxyurea Sensitivity in Escherichia coli K-12

Understanding the functions of all genes and their biological mechanisms based on comprehensive genome regulation mechanisms is an important issue in life sciences. YnfL is an uncharacterized LysR family transcription factor in <i>Escherichia coli</i>. Genomic SELEX screening was performed to identify YnfL regulatory targets in the <i>E. coli</i> genome and reveal the function of YnfL. Nine loci on the <i>E. coli</i> genome were identified as regulatory targets of YnfL, and the target genes were involved in supplying DNA substrates and DNA repair. RT-qPCR analysis in vivo revealed that YnfL activates its target genes during the stationary phase. Tests for drug resistance that causes DNA damage revealed that <i>ynfL</i> deficiency increased abnormal cell filamentation and the appearance of anucleate cells in the presence of hydroxyurea. Furthermore, <i>ynfL</i> deficiency reduced cell survival under long-term nitrogen starvation conditions. In summary, we propose renaming <i>ynfL</i> to hydroxyurea sensitivity regulator (<i>husR</i>). These findings contribute to understanding DNA maintenance and long-term survival through transcriptional regulation.