Transcription Factor SrsR (YgfI) Is a Novel Regulator for the Stress-Response Genes in Stationary Phase in Escherichia coli K-12.

Understanding the functional information of all genes and the biological mechanism based on the comprehensive genome regulation mechanism is an important task in life science. YgfI is an uncharacterized LysR family transcription factor in Escherichia coli . To identify the function of YgfI, the genomic SELEX (gSELEX) screening was performed for YgfI regulation targets on the E. coli genome. In addition, regulatory and phenotypic analyses were performed. A total of 10 loci on the E. coli genome were identified as the regulatory targets of YgfI with the YgfI binding activity. These predicted YgfI target genes were involved in biofilm formation, hydrogen peroxide resistance, and antibiotic resistance, many of which were expressed in the stationary phase. The TCAGATTTTGC sequence was identified as an YgfI box in in vitro gel shift assay and DNase-I footprinting assays. RT-qPCR analysis in vivo revealed that the expression of YgfI increased in the stationary phase. Physiological analyses suggested the participation of YgfI in biofilm formation and an increase in the tolerability against hydrogen peroxide. In summary, we propose to rename ygfI as srsR (a stress-response regulator in stationary phase).