Role of transcription factor NimR (YeaM) in sensitivity control of Escherichia coli to 2-nitroimidazole

Abstract

The binding site(s) on the Escherichia coli genome was determined for an uncharacterized AraC/XylS superfamily transcription factor YeaM by using the in vitro genomic SELEX screening system. The only one clear binding target of YeaM was found to locate in the spacer between the divergently transcribed yeaM and yeaN genes. After the phenotype microarray analysis, the major facilitator superfamily transporter YeaN was found to confer E. coli the resistance to 2-nitroimidazole, the antibacterial and antifungal antibiotic, suggesting that YeaN plays a role in 2-nitromidazole efflux. Purified YeaM bound to three sites within this yeaM-yeaN spacer region. Several lines of in vitro and in vivo evidence indicate that YeaM regulates transcription of both the yeaM gene itself and the yeaNO operon. Taken together we propose to rename yeaN to nimT (nitroimidazole transporter) and yeaM to nimR (regulator of nimT).