N-Acetyl-d-Glucosamine Induces the Expression of Multidrug Exporter Genes,mdtEF, via Catabolite Activation inEscherichia coli

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Abstract
The expression of MdtEF, a multidrug exporter inEscherichia coli, is positively controlled through multiple signaling pathways, but little is known about signals that induce MdtEF expression. In this study, we investigated compounds that induce the expression of themdtEFgenes and found that out of 20 drug exporter genes inE. coli, the expression ofmdtEFis greatly induced byN-acetyl-d-glucosamine (GlcNAc). The induction ofmdtEFby GlcNAc is not mediated by theevgSA,ydeO,gadX, andrpoSsignaling pathways that have been known to regulatemdtEFexpression. On the other hand, deletion of thenagEgene, encoding the phosphotransferase (PTS) system for GlcNAc, prevented induction by GlcNAc. The induction ofmdtEFby GlcNAc was also greatly inhibited by the addition of cyclic AMP (cAMP) and completely abolished upon deletion of the cAMP receptor protein gene (crp). Other PTS sugars, glucose andd-glucosamine, also inducedmdtEFgene expression. These results suggest thatmdtEFexpression is stimulated through catabolite control.