The transcription factor NemR is an electrophile-sensing regulator important for the detoxification of reactive electrophiles in Acinetobacter nosocomialis

Abstract NemR is an electrophile-sensing regulator which controls two enzymes required for the detoxification of reactive electrophiles: N-ethylmaleimide (NEM) reductase and glyoxalase I in Escherichia coli . Both enzymes are essential for bacterial survival in the presence of toxic reactive electrophiles, such as N-ethylmaleimide and methyl glyoxal. Here, we report the identification and characterization of NemR from Acinetobacter nosocomialis , a nosocomial pathogen. We confirmed that nemR and the nemA gene which encodes N-ethylmaleimide reductase form a single operon, which is in accordance with the reports from E. coli . Bioinformatic analysis revealed the presence of an NemR binding motif in the promoter regions of nemRA operon and gloA (encoding glyoxalase I) and the binding was confirmed by gel mobility shift assay. The deletion of nemR resulted in increased biofilm/pellicle formation in A. nosocomialis . mRNA expression analysis revealed that NemR acts as a repressor of the nemRA operon and gloA , and that the repressor function is inactivated by the addition of toxic Cys modification agents, contributing to bacterial survival. In addition, it was demonstrated that the nemRA operon is positively regulated by the quorum sensing regulator, AnoR and the operon plays a role in biofilm/pellicle formation in A. nosocomialis .