Que Q, Helmann J D
Section of Microbiology, Wing Hall, Cornell University, Ithaca, NY 14853-8101, USA.
Mol Microbiol. 2000 Mar;35(6):1454-68. doi: 10.1046/j.1365-2958.2000.01811.x.
The Bacillus subtilis yqhN gene encodes a metalloregulatory protein distantly related to the Corynebacterium diphtheriae diphtheria toxin repressor (DtxR). While DtxR mediates the iron-dependent repression of iron uptake, we demonstrate that yqhN (herein renamed mntR) encodes a manganese modulated regulator of manganese transport. An mntR mutant strain is sensitive to both manganese and cadmium, suggesting that the transport of these metals is derepressed. We selected Tn10 insertions that suppress the Mn(II) sensitivity of the mntR mutant or that increase the Cd(II) tolerance of wild-type cells, and in both cases we recovered insertions in mntH (formerly ydaR). MntH is a member of the NRAMP family of proton-coupled, metal ion transporters. MntR also regulates expression of a Mn(II) ABC transporter (MntABCD). The MntH and MntABCD transporters are both selectively repressed by Mn(II) and this regulation requires MntR. In high Mn(II) conditions, MntR functions as a Mn(II)-dependent repressor of mntH transcription. In contrast, MntR acts as a positive regulator of the mntABCD operon under low Mn(II) growth conditions. Biochemical studies demonstrate that MntR binding to the mntH control region requires Mn(II), while interaction with the mntABCD control region does not depend on Mn(II).
枯草芽孢杆菌yqhN基因编码一种与白喉棒状杆菌白喉毒素阻遏物(DtxR)有远缘关系的金属调节蛋白。虽然DtxR介导铁摄取的铁依赖性阻遏,但我们证明yqhN(在此重新命名为mntR)编码一种锰转运的锰调节因子。mntR突变株对锰和镉都敏感,这表明这些金属的转运不受抑制。我们选择了能抑制mntR突变株对Mn(II)敏感性或能提高野生型细胞对Cd(II)耐受性的Tn10插入突变,在这两种情况下,我们都在mntH(以前的ydaR)中发现了插入突变。MntH是质子偶联金属离子转运蛋白NRAMP家族的成员。MntR还调节Mn(II) ABC转运蛋白(MntABCD)的表达。MntH和MntABCD转运蛋白都被Mn(II)选择性抑制,这种调节需要MntR。在高Mn(II)条件下,MntR作为mntH转录的Mn(II)依赖性阻遏物发挥作用。相反,在低Mn(II)生长条件下,MntR作为mntABCD操纵子的正调节因子起作用。生化研究表明,MntR与mntH控制区的结合需要Mn(II),而与mntABCD控制区的相互作用不依赖于Mn(II)。