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首页> 外文期刊>Journal of bacteriology >Transcriptional Regulation of sitABCD of Salmonella enterica Serovar Typhimurium by MntR and Fur
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Transcriptional Regulation of sitABCD of Salmonella enterica Serovar Typhimurium by MntR and Fur

机译：MntR和Fur对肠炎沙门氏菌鼠伤寒沙门氏菌sitABCD的转录调控

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Salmonella enterica serovar Typhimurium has two manganese transport systems, MntH and SitABCD. MntH is a bacterial homolog of the eukaryotic natural resistance-associated macrophage protein 1 (Nramp1), and SitABCD is an ABC-type transporter. Previously we showed that mntH is negatively controlled at the transcriptional level by the trans-acting regulatory factors, MntR and Fur. In this study, we examined the transcriptional regulation of sitABCD and compared it to the transcriptional regulation of mntH by constructing lacZ fusions to the promoter regions with and without mutations in putative MntR and/or Fur binding sites. The presence of Mn caused transcriptional repression of the sitABCD and mntH promoters primarily via MntR, but Fur was also capable of some repression in response to Mn. Likewise, Fe in the medium repressed transcription of both sit and mntH primarily via Fur, although MntR was also involved in this response. Transcriptional control by MntR and Fur was disrupted by site-specific mutations in the putative MntR and Fur binding sites, respectively. Transcription of the sit operon was also affected by the oxygen level and growth phase, but the increased expression observed under high oxygen conditions and higher cell densities is consistent with decreased availability of metals required for repression by the metalloregulatory proteins.
机译：鼠伤寒沙门氏菌有两个锰转运系统，MntH和SitABCD。 MntH是与真核生物自然抗性相关的巨噬细胞蛋白1（Nramp1）的细菌同源物，而SitABCD是ABC型转运蛋白。先前我们证明了 mntH 在转录水平上受 trans 作用调节因子MntR和Fur的负调控。在这项研究中，我们研究了 sitABCD 的转录调控，并通过与启动子区域构建 lacZ 融合体，将其与 mntH 的转录调控进行了比较。并且在假定的MntR和/或Fur结合位点无突变。 Mn的存在主要通过MntR引起 sitABCD 和 mntH 启动子的转录抑制，但是Fur也能够响应Mn而具有一定的抑制作用。同样，尽管MntR也参与了该反应，但培养基中的Fe主要通过Fur抑制了 sit 和 mntH 的转录。 MntR和Fur的转录控制分别被假定的MntR和Fur结合位点的位点特异性突变所破坏。 sit 操纵子的转录也受氧水平和生长期的影响，但在高氧条件下和较高的细胞密度下观察到的表达增加与金属调控蛋白抑制所需金属的可用性降低是一致的。

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