RESUMEN
The expression of MdtEF, a multidrug exporter in Escherichia 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 the mdtEF genes and found that out of 20 drug exporter genes in E. coli, the expression of mdtEF is greatly induced by N-acetyl-d-glucosamine (GlcNAc). The induction of mdtEF by GlcNAc is not mediated by the evgSA, ydeO, gadX, and rpoS signaling pathways that have been known to regulate mdtEF expression. On the other hand, deletion of the nagE gene, encoding the phosphotransferase (PTS) system for GlcNAc, prevented induction by GlcNAc. The induction of mdtEF by 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 and d-glucosamine, also induced mdtEF gene expression. These results suggest that mdtEF expression is stimulated through catabolite control.
Asunto(s)
Acetilglucosamina/farmacología , Factor de Transcripción de AraC/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Proteínas de la Membrana/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Proteínas Quinasas/metabolismo , Factor de Transcripción de AraC/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteína Receptora de AMP Cíclico , Farmacorresistencia Bacteriana , Escherichia coli/efectos de los fármacos , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica , Proteínas de la Membrana/genética , Proteínas de Transporte de Membrana/genética , Proteínas Quinasas/genética , Factor sigma/genética , Factor sigma/metabolismo , Transducción de Señal , Factores de TranscripciónRESUMEN
Our comprehensive expression cloning studies previously revealed that 20 intrinsic xenobiotic exporter systems are encoded in the Escherichia coli chromosome, but most of them are not expressed under normal conditions. In this study, we investigated the compounds that induce the expression of these xenobiotic exporter genes, and found that indole induces a variety of xenobiotic exporter genes including acrD, acrE, cusB, emrK, mdtA, mdtE and yceL. Indole treatment of E. coli cells confers rhodamine 6G and SDS resistance through the induction of mdtEF and acrD gene expression respectively. The induction of mdtE by indole is independent of the EvgSA two-component signal transduction system that regulates the mdtE gene, but mediated by GadX. On the other hand, the induction of acrD and mdtA was mediated by BaeSR and CpxAR, two-component systems. Interestingly, CpxAR system-mediated induction required intrinsic baeSR genes, whereas BaeSR-mediated induction was observed in the cpxAR gene-deletion mutant. BaeR and CpxR directly bound to different sequences of the acrD and mdtA promoter regions. These observations indicate that BaeR is a primary regulator, and CpxR enhances the effect of BaeR.
Asunto(s)
Escherichia coli/genética , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Indoles/farmacología , Proteínas Asociadas a Resistencia a Múltiples Medicamentos/genética , Secuencia de Bases , Cromosomas Bacterianos/genética , Huella de ADN , Desoxirribonucleasa I , Escherichia coli/efectos de los fármacos , Proteínas de Escherichia coli/genética , Mutagénesis Sitio-Dirigida , Plásmidos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Xenobióticos/farmacocinéticaRESUMEN
The response regulator EvgA controls expression of multiple genes conferring antibiotic resistance in Escherichia coli (K. Nishino and A. Yamaguchi, J. Bacteriol. 184:2319-2323, 2002). To understand the whole picture of EvgA regulation, DNA macroarray analysis of the effect of EvgA overproduction was performed. EvgA activated genes related to acid resistance, osmotic adaptation, and drug resistance.