Molecular characterization of the Mg2+-responsive PhoP-PhoQ regulon in Salmonella enterica
Molecular characterization of the Mg2+-responsive PhoP-PhoQ regulon in Salmonella enterica
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DOI：
10.1128/jb.185.21.6287-6294.2003
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发表时间：
2003-11-01
影响因子：
3.2
通讯作者：
Soncini, FC
中科院分区：
文献类型：
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作者：
Lejona, S;Aguirre, A;Soncini, FC
PhoP/PhoQ双组分系统控制沙门氏菌胞外镁剥夺反应此外，在感染过程中主要需要巨噬细胞内存活的几个毒力相关基因在其转录调控下。尽管共享Mg 2+调制的PhoP激活基因的表达，没有共识的序列，所有的人都可以检测到在其启动子区。我们已经调查了转录调控和相互作用的反应调节Phol？与PhoP激活的基因座phoPQ、mgtA、slyB、pmrD、pcgL、phoN、pagC和mgtCB的启动子区。七核苷酸序列的直接重复（G/T）GTTTA（A/T）被鉴定为PhoP识别的保守基序，直接控制前5个位点的基因表达，其中前4个是肠杆菌的祖先。另一方面，没有直接的相互作用的反应调节与phoN，pagC，或mgtCB的启动子是明显的，无论是在体外或体内试验。这些位点是沙门氏菌特异性的，可能是通过水平DNA转移获得的。此外，对pag启动子的序列分析显示，在所分析的12个基因中，有6个基因存在保守的PhoP盒。我们的研究结果强烈表明，一组Mg 2+控制的基因的表达是由PhoP通过未知的中间调控机制，也可能涉及辅助因素。
The PhoP/PhoQ two-component system controls the extracellular magnesium deprivation response in Salmonella enterica. In addition, several virulence-associated genes that are mainly required for intramacrophage survival during the infection process are under the control of its transcriptional regulation. Despite shared Mg2+ modulation of the expression of the PhoP-activated genes, no consensus sequence common to all of them could be detected in their promoter regions. We have investigated the transcriptional regulation and the interaction of the response regulator Phol? with the promoter regions of the PhoP-activated loci phoPQ, mgtA, slyB, pmrD, pcgL, phoN, pagC, and mgtCB. A direct repeat of the heptanucleotide sequence (G/T) GTTTA(A/T) was identified as the conserved motif recognized by PhoP to directly control the gene expression of the first five loci, among which the first four are ancestral to enterobacteria. On the other hand, no direct interaction of the response regulator with the promoter of phoN, pagC, or mgtCB was apparent by either in vitro or in vivo assays. These loci are Salmonella specific and were probably acquired by horizontal DNA transfer. Besides, sequence analysis of pag promoters revealed the presence of a conserved PhoP box in 6 out of the 12 genes analyzed. Our results strongly suggest that the expression of a set of Mg2+-controlled genes is driven by PhoP via unknown intermediate regulatory mechanisms that could also involve ancillary factors.