LeuO antagonizes H-NS and StpA-dependent repression in Salmonella enterica ompS1
LeuO antagonizes H-NS and StpA-dependent repression in Salmonella enterica ompS1
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DOI：
10.1111/j.1365-2958.2007.05958.x
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发表时间：
2007-11-01
影响因子：
3.6
通讯作者：
Calva, Edmundo
中科院分区：
文献类型：
--
作者：
De la Cruz, Miguel Angel;Fernandez-Mora, Marcos;Calva, Edmundo
ompS1基因在肠沙门氏菌中编码一个静止的孔蛋白。我们分析了H-NS和StpA （H-NS的同源物）对ompS1表达的影响。在hns中，单突变体表达被抑制，但未达到最大水平。stpA单突变体的表达水平与野生型一样低。相反，在非stpA背景下，OmpS1在外膜中变得丰富。ompS1的表达受到LeuO的正调控，LeuO是一种参与发病机制的lysr型静止调节因子。将克隆的leuO基因导入野生型后，ompS1基因被完全抑制，外膜中检测到ompS1孔蛋白。LeuO以OmpR依赖的方式激活P1启动子，而在没有OmpR的情况下激活P2启动子。LeuO结合在ompS1调控区的上游，与H-NS和StpA的一个成核位点重叠。因此，我们的结果与H-NS在成核位点结合，LeuO取代H-NS和StpA的模型一致。
The ompS1 gene encodes a quiescent porin in Salmonella enterica. We analysed the effects of H-NS and StpA, a paralogue of H-NS, on ompS1 expression. In an hns single mutant expression was derepressed but did not reach the maximum level. Expression in an stpA single mutant showed the same low repressed level as the wild type. In contrast, in an hns stpA background, OmpS1 became abundant in the outer membrane. The expression of ompS1 was positively regulated by LeuO, a LysR-type quiescent regulator that has been involved in pathogenesis. Upon induction of the cloned leuO gene into the wild type, ompS1 was completely derepressed and the OmpS1 porin was detected in the outer membrane. LeuO activated the P1 promoter in an OmpR-dependent manner and P2 in the absence of OmpR. LeuO bound upstream of the regulatory region of ompS1 overlapping with one nucleation site of H-NS and StpA. Our results are thus consistent with a model where H-NS binds at a nucleation site and LeuO displaces H-NS and StpA.