PhoP-induced genes within Salmonella pathogenicity island 1
PhoP-induced genes within Salmonella pathogenicity island 1
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DOI：
10.1128/jb.00804-06
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发表时间：
2006-10-01
影响因子：
3.2
通讯作者：
Soncini, Fernando C.
中科院分区：
文献类型：
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作者：
Aguirre, Andres;Cabeza, Maria Laura;Soncini, Fernando C.
侵袭性病原体肠道沙门氏菌已经进化出一种复杂的设备，使其能够进入非吞噬宿主细胞。这一过程需要沙门氏菌致病岛I(SPI-1)的表达，它编码一个专门的III型蛋白分泌系统(TTSS)。这种TTSS提供了一系列效应器，使宿主细胞骨架发生明显的重排，在相互作用的部位产生大量的膜褶皱，推动细菌进入。已有研究表明，Phop/PhoQ双组分系统通过下调其主要调控因子Hila的转录来抑制SPI-1机制的表达。在这部作品中，我们揭示了。SPI-1中存在一个由光子激活的操纵子。这个操纵子由orgB和orgC基因组成，它们分别编码一个与InvC ATPase相互作用的蛋白和一个可能的TTSS效应蛋白。在Phop诱导的条件下，这种操纵子的表达直接被识别Phol？的反应调节因子的磷酸化形式激活。框位于转录起始点的-35区域。此外，在侵袭诱导条件下，orgBC的表达既由SPI-1主调控子HiIA诱导的prgH启动子驱动，也由直接控制的Phop/PhoQ启动子驱动。综上所述，这些结果表明，与SPI-1基因座中的其他基因不同，orgBC在沙门氏菌进入宿主细胞期间和之后表达，这些结果表明该操纵子的产物在宿主细胞内化后发挥作用。
The invasive pathogen Salmonella enterica has evolved a sophisticated device that allows it to enter nonphagocytic host cells. This process requires the expression of Salmonella pathogenicity island I (SPI-1), which encodes a specialized type III protein secretion system (TTSS). This TTSS delivers a set of effectors that produce a marked rearrangement of the host cytoskeleton, generating a profuse membrane ruffling at the site of interaction, driving bacterial entry. It has been shown that the PhoP/PhoQ two-component system represses the expression of the SPI-1 machinery by down-regulating the transcription of its master regulator, HilA. In this work, we reveal. the presence of a PhoP-activated operon within SPI-1. This operon is composed of the orgB and orgC genes, which encode a protein that interacts with the InvC ATPase and a putative effector protein of the TTSS, respectively. Under PhoP-inducing conditions, expression of this operon is directly activated by the phosphorylated form of the response regulator, which recognizes a Phol? box located at the -35 region relative to the transcription start site. Additionally, under invasion-inducing conditions, orgBC expression is driven both by the prgH promoter, induced by the SPI-1 master regulator HiIA, and by the directly controlled PhoP/PhoQ promoter. Together, these results indicate that in contrast to the rest of the genes encompassed in the SPI-1 locus, orgBC is expressed during and after Salmonella entry into its host cell, and they suggest a role for the products of this operon after host cell internalization.