title: A copper-responsive global repressor regulates expression of diverse membrane-associated transporters and bacterial drug resistance in mycobacteria.
abstract: Sequencing of entire bacterial genomes has led to the identification of many membrane-associated transporters, including several multidrug resistance transport proteins, in recent years. However, the regulators and signaling pathways involved in the expression of these genes remain largely unknown. In this study, we have identified Ms2173, a GntR/FadR family transcription factor, as a novel global regulator in Mycobacterium smegmatis. Ms2173 was found to specifically recognize a 15-bp palindromic motif and to broadly regulate expression of 292 genes, including 37 genes that encode membrane-associated transport proteins. Copper ions induced Ms2173 to form inactive proteins lacking DNA-binding activity. Ms2173 was shown to function as a repressor of its target genes. Interestingly, we found that the function of Ms2173 was linked to mycobacterial drug resistance. Compared with the substantially enhanced drug resistance in the Ms2173-deleted mutant strain, the strains overexpressing Ms2173 were more sensitive to anti-tuberculosis drugs than the wild-type strain. Additionally, copper ions could partially counteract the in vivo function of Ms2173. We have thus characterized the first mycobacterial GntR/Fad-like transcription factor that functions as a copper ion-responsive global repressor that we have renamed GfcR. These findings further enhance our understanding of membrane-associated transporter regulation and drug resistance in mycobacteria.
authors.affiliation: National Key Laboratory of Agricultural Microbiology, Center for Proteomics Research, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Muding
authors.initials: M
authors.lastname: Rao
authors.forename: Huicong
authors.initials: H
authors.lastname: Liu
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.forename: Chunchao
authors.initials: C
authors.lastname: Zhao
authors.forename: Zheng-Guo
authors.initials: ZG
authors.lastname: He
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D003300:Copper / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000187:drug effects / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000502:physiology*; D008667:Metalloproteins / Q000235:genetics / Q000378:metabolism*; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000502:physiology*
chemical_list: D000995:Antitubercular Agents; D001426:Bacterial Proteins; D002352:Carrier Proteins; D008667:Metalloproteins; D012097:Repressor Proteins; D003300:Copper