초록
<P><B>ABSTRACT</B><P><I>N</I> -Acetylglucosamine (GlcNAc) is the most abundant carbon-nitrogen biocompound on earth and has been shown to be an important source of nutrients for both catabolic and anabolic purposes in Bacillus species. In this work we show that the GntR family regulator YvoA of Bacillus subtilis serves as a negative transcriptional regulator of GlcNAc catabolism gene expression. YvoA represses transcription by binding a 16-bp sequence upstream of <I>nagP</I> encoding the GlcNAc-specific EIIBC component of the sugar phosphotransferase system involved in GlcNAc transport and phosphorylation, as well as another very similar 16-bp sequence upstream of the <I>nagAB-yvoA</I> locus, wherein <I>nagA</I> codes for <I>N</I> -acetylglucosamine-6-phosphate deacetylase and <I>nagB</I> codes for the glucosamine-6-phosphate (GlcN-6-P) deaminase. <I>In vitro</I> experiments demonstrated that GlcN-6-P acts as an inhibitor of YvoA DNA-binding activity, as occurs for its Streptomyces ortholog, DasR. Interestingly, we observed that the expression of <I>nag</I> genes was still activated upon addition of GlcNAc in a Δ <I>yvoA</I> mutant background, suggesting the existence of an auxiliary transcriptional control instance. Initial computational prediction of the YvoA regulon showed a distribution of YvoA binding sites limited to <I>nag</I> genes and therefore suggests renaming YvoA to NagR, for <I>N</I> -acetylglucosamine utilization regulator. Whole-transcriptome studies showed significant repercussions of <I>nagR</I> deletion for several major B. subtilis regulators, probably indirectly due to an excess of the crucial molecules acetate, ammonia, and fructose-6-phosphate, resulting from complete hydrolysis of GlcNAc. We discuss a model deduced from NagR-mediated gene expression, which highlights clear connections with pathways for GlcNAc-containing polymer biosynthesis and adaptation to growth under oxygen limitation. </P></P>