The Uncharacterized Transcription Factor YdhM Is the Regulator of the nemA Gene, Encoding N -Ethylmaleimide Reductase

Abstract

N-Ethylmaleimide (NEM) has been used as a specific reagent of Cys modification in proteins and thus is toxic for cell growth. On the Escherichia coli genome, the nemA gene coding for NEM reductase is located downstream of the gene encoding an as-yet-uncharacterized transcription factor, YdhM. Disruption of the ydhM gene results in reduction of nemA expression even in the induced state, indicating that the two genes form a single operon. After in vitro genomic SELEX screening, one of the target recognition sequences for YdhM was identified within the promoter region for this ydhM-nemA operon. Both YdhM binding in vitro to the ydhM promoter region and transcription repression in vivo of the ydhM-nemA operon by YdhM were markedly reduced by the addition of NEM. Taken together, we propose that YdhM is the repressor for the nemA gene, thus hereafter designated NemR. The repressor function of NemR was inactivated by the addition of not only NEM but also other Cys modification reagents, implying that Cys modification of NemR renders it inactive. This is an addition to the mode of controlling activity of transcription factors by alkylation with chemical agents.

Participation of Regulator AscG of the β-Glucoside Utilization Operon in Regulation of the Propionate Catabolism Operon

“…with the binding affinity of the test transcription factor to the substrate DNA (36,44). If this is the case with AscG, then the prp operon must be a major regulation target of AscG, in addition to the asc operon.…”

SearchDOGS Bacteria, Software That Provides Automated Identification of Potentially Missed Genes in Annotated Bacterial Genomes

“…This gene codes for N-ethylmaleimide reductase, a member of the "Old Yellow Enzyme" family (42). It plays a role in the beta-oxidation of fatty acids by being involved in reductive degradation of toxic nitrous compounds (43,44) and is regulated by nemR. The nemA-nemR operon is present in every species in this study except S. boydii, where nemR is present but nemA is annotated as a pseudogene truncated by an in-frame stop codon at position 101 of 367 (30).…”

Study of the role played by NfsA, NfsB nitroreductase and NemA flavin reductase from Escherichia coli in the conversion of ethyl 2-(2′-nitrophenoxy)acetate to 4-hydroxy-(2H)-1,4-benzoxazin-3(4H)-one (D-DIBOA), a benzohydroxamic acid with interesting biological properties

“…In the last few years, these enzymes have received attention due to their environmental, biotechnological and clinical applications (Roldán et al 2008). These enzymes are thought to participate in oxidative stress response (Liochev et al 1994(Liochev et al , 1999, although their physiological role has not been elucidated yet (Umezawa et al 2008). Nitroreductases could also be involved in the reduction of non-natural substrates as xenobiotic compounds released by humans activities in the recent years (Rau and Stolz 2003).…”