Role of the extracytoplasmic function protein family sigma factor RpoE in metal resistance of Escherichia coli
Role of the extracytoplasmic function protein family sigma factor RpoE in metal resistance of Escherichia coli
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DOI：
10.1128/jb.187.7.2297-2307.2005
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发表时间：
2005-04-01
影响因子：
3.2
通讯作者：
Nies, DH
中科院分区：
文献类型：
--
作者：
Egler, M;Grosse, C;Nies, DH
大肠杆菌的RpoE是胞质外功能蛋白家族的σ因子，并且是参与维持周质和外膜组分的完整性的蛋白质的表达所需的。E的RpoE。大肠杆菌对Zn（II）、Cd（II）和Cu（II）的完全抗性是必需的。启动子基因融合和定量真实的时间逆转录（RT）-PCR（qRT-PCR）测定表明RpoE的表达受到金属的诱导。用微阵列分析Delta rpoE突变株及其野生型菌株在金属处理后的全局基因表达谱，并通过qRT-PCR确认所选基因。在金属胁迫后表达改变的基因的绝对数量在两种菌株中是相似的，但是在金属处理后转录水平的增加或减少在Delta rpoE突变菌株中比在野生型中更小。在Delta rpoE突变株中表现出表达增加的基因编码的蛋白质属于针对蛋白质变性剂的一般防御系统。显示表达降低的基因是RpoE调制子本身加上ompC基因的一部分，ompC基因编码一种主要的外膜蛋白。Δ ompC缺失菌株对Cu（II）和Cd（II）的敏感性与Δ rpoE突变体或Δ rpoE Δ ompC双突变菌株相同。在Zn（II）的情况下，双突变体比单突变体更敏感。这表明OmpC的表达增加有助于RpoE模块介导的对金属的响应。
RpoE of Escherichia coli is a sigma factor of the extracytoplasmic function protein family and is required for the expression of proteins involved in maintaining the integrity of periplasmic and outer membrane components. RpoE of E. coli was needed for full resistance to Zn(II), Cd(II), and Cu(II). Promoter gene fusion and quantitative real time reverse transcription (RT)-PCR (qRT-PCR) assays demonstrated that expression of RpoE was induced by metals. Global gene expression profiles upon metal treatment of a Delta rpoE mutant strain and its wild-type strain were analyzed with microarrays, and selected genes were confirmed by qRT-PCR. The absolute number of genes that were changed in their expression upon metal stress was similar in both strains, but the increase or decrease in transcript levels upon metal treatment was smaller in the Delta rpoE mutant strain than in the wild type. Genes showing increased expression in the Delta rpoE mutant strain encoded proteins that belong to general defense systems against protein-denaturing agents. Genes showing decreased expression were part of the RpoE modulon itself plus the ompC gene, encoding a major outer membrane protein. A Delta ompC deletion strain was as sensitive to Cu(II) and Cd(II) as the Delta rpoE mutant or a Delta rpoE Delta ompC double mutant strain. In the case of Zn(II), the double mutant was more sensitive than either single mutant. This indicates that increased expression of OmpC contributes to the RpoE modulon-mediated response to metals.