title: Bacillus subtilis MntR coordinates the transcriptional regulation of manganese uptake and efflux systems.
abstract: The Bacillus subtilis MntR metalloregulatory protein senses manganese, an essential element required for central metabolism, oxidative stress resistance and replication. An mntR null mutant is highly sensitive to Mn(II) intoxication, which is attributed in part to the constitutive expression of two importers: the proton-dependent NRAMP family transporter MntH and the ABC transporter MntABCD. Here, we show that an mntR null mutant is still sensitive to Mn(II) intoxication even if both of the import systems are absent. This Mn(II) sensitivity results from the requirement for MntR to activate the transcription of two genes encoding cation diffusion facilitator (CDF) family efflux pumps. Physiological studies indicate that MneP (formerly YdfM) serves as the primary Mn(II) efflux pump with MneS (formerly YeaB) playing a secondary role. Mutant strains lacking mneP are Mn(II) sensitive and accumulate elevated levels of Mn(II), and these effects are exacerbated in a mneP mneS double mutant. DNA-binding and in vitro transcription studies demonstrate that MntR binds to both the mneP and mneS regulatory regions and directly activates transcription in response to levels of Mn(II) several-fold higher than required for repression of import genes. These results highlight the delicate balance of Mn(II) uptake and efflux systems controlled by MntR.
authors.affiliation: Cornell University, Department of Microbiology, Ithaca, NY, 14853-8101, USA.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Huang
authors.affiliation: Cornell University, Department of Microbiology, Ithaca, NY, 14853-8101, USA.
authors.forename: Jung-Ho
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Cornell University, Department of Microbiology, Ithaca, NY, 14853-8101, USA.
authors.forename: Azul
authors.initials: A
authors.lastname: Pinochet-Barros
authors.affiliation: Cornell University, Department of Microbiology, Ithaca, NY, 14853-8101, USA.
authors.forename: Tina T
authors.initials: TT
authors.lastname: Su
authors.affiliation: Cornell University, Department of Microbiology, Ithaca, NY, 14853-8101, USA.
authors.forename: John D
authors.identifier: 0000-0002-3832-3249
authors.initials: JD
authors.lastname: Helmann
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D027682:Cation Transport Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008345:Manganese / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D027682:Cation Transport Proteins; C433792:MntR protein, bacteria; D012097:Repressor Proteins; D008345:Manganese