Comparison of the PhoPQ regulon in Escherichia coli and Salmonella typhimurium
Comparison of the PhoPQ regulon in Escherichia coli and Salmonella typhimurium
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DOI：
10.1007/s00239-004-0212-7
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发表时间：
2005-04-01
影响因子：
3.9
通讯作者：
Marchal, K
中科院分区：
文献类型：
--
作者：
Monsieurs, P;De Keersmaecker, S;Marchal, K
PhoPQ双组分系统在大肠杆菌和鼠伤寒沙门氏菌中均作为应答Mg 2+饥饿的转录调节子（Garcia等人，1996; Kato等人，1999）。通过监测细胞外Mg 2+的可用性，该双组分系统允许S.鼠伤寒沙门氏菌感受从细胞外环境到亚细胞位置的转变。伴随着这种转变，一组在细胞内环境中生存所必需的毒力因子被PhoPQ系统激活（Groisman等，1989;米勒等，1989）。与非致病性菌株如E. coli K12中，病原体中的PhoPQ调节子必须含有特异性贡献毒力表型的靶基因。为了验证这一假设，我们比较了大肠杆菌PhoPQ调节子的组成。coli和革兰氏阳性菌S.使用表达实验和基序数据的组合。通过PhoPQ相关的微阵列实验，鉴定了两种生物体中的PhoPQ依赖性基因。为了区分直接和间接靶点，我们在已鉴定的PhoPQ依赖性基因的启动子区域中搜索调控基序的存在。这使我们能够重建E. coli K12和S.鼠伤寒LT 2。两种调节子的比较揭示了两种生物之间PhoPQ依赖性基因的非常有限的重叠。这些结果表明，在这些密切相关的物种中，PhoPQ系统在进化过程中获得了一种特殊的功能，从而能够适应其生活方式的特殊性（例如，S.鼠伤寒）。
The PhoPQ two-component system acts a transcriptional regulator that responds to Mg2+ starvation both in Escherichia coli and Salmonella typhimurium (Garcia et al. 1996; Kato et al. 1999). By monitoring the availability of extracellular Mg2+, this two-component system allows S. typhimurium to sense the transition from an extracellular environment to a subcellular location. Concomitantly with this transition, a set of virulence factors essential for survival in the intracellular environment is activated by the PhoPQ system (Groisman et al. 1989; Miller et al. 1989). Compared to nonpathogenic strains, such as E. coli K12, the PhoPQ regulon in pathogens must contain target genes specifically contributing, to the virulence phenotype. To verify this hypothesis, we compared the composition of the PhoPQ regulon between E. coli and S. typhimurium using a combination of expression experiments and motif data. PhoPQ-dependent genes in both organisms were identified from PhoPQ-related microarray experiments. To distinguish between direct and indirect targets, we searched for the presence of the regulatory motif in the promoter region of the identified PhoPQ-dependent genes. This allowed us to reconstruct the direct PhoPQ-dependent regulons in E. coli K12 and S. typhimurium LT2. Comparison of both regulons revealed a very limited overlap of PhoPQ-dependent genes between both organisms. These results suggest that the PhoPQ system has acquired a specialized function during evolution in each of these closely related species that allows adaptation to the specificities of their lifestyles (e.g., pathogenesis in S. typhimurium).