Identification of the P3 Promoter and Distinct Roles of the Two Promoters of the SaeRS Two-Component System in Staphylococcus aureus
Identification of the P3 Promoter and Distinct Roles of the Two Promoters of the SaeRS Two-Component System in Staphylococcus aureus
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DOI：
10.1128/jb.00353-11
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发表时间：
2011-09-01
影响因子：
3.2
通讯作者：
Bae, Taeok
中科院分区：
文献类型：
--
作者：
Jeong, Do-Won;Cho, Hoonsik;Bae, Taeok
在金黄色葡萄球菌中，由saePQRS操纵子编码的SaeRS双组分系统（TCS）控制凝血酶和α溶血素等主要毒力因子的表达。saePQRS操纵子有两个启动子：P1和P3。P1启动子是一种强启动子，是自动诱导的，可以转录所有四个基因。与P1相比，P3的启动子活性较低，但具有组成性，它只转录saeR和saeS，这两个基因分别编码应答调节因子saeR和传感器激酶saeS。然而，每个启动子在sae信号传导中的作用尚未得到严格定义。在这项研究中，我们发现P3的真正转录起始位点（TSS）位于之前报道的TSS下游78个核苷酸。随后，通过诱变分析鉴定并验证了P3启动子序列。包括P1启动子在内的saePQ区域的缺失并没有显著改变凝固酶和α溶血素这两个众所周知的sae靶基因的表达模式。由于其在跨膜结构域的L18P取代，菌株Newman中的SaeS具有组成激酶活性。有趣的是，突变也使蛋白质不稳定，但SaeQ恢复了蛋白质的稳定性，这表明可能存在SaeQ- saes相互作用。具有讽刺意味的是，同样的突变似乎增加了mRNA的稳定性。SaeR似乎被SaeS稳定，可能是通过蛋白质-蛋白质相互作用。P1染色体突变不影响凝固酶和α -溶血素的表达模式。基于这些结果，我们得出结论，P3的saeRS转录足以激活靶基因，P1不参与激活。
In Staphylococcus aureus, the SaeRS two-component system (TCS) encoded by the saePQRS operon controls expression of major virulence factors, such as coagulase and alpha-hemolysin. The saePQRS operon has two promoters: P1 and P3. The P1 promoter, a strong promoter, is autoinduced and can transcribe all four genes. Compared with P1, P3 shows fairly low but constitutive promoter activity, and it transcribes only saeR and saeS, the two genes encoding response regulator SaeR and sensor kinase SaeS. However, the role of each promoter in sae signaling has not been rigorously defined. In this study, we found that the genuine transcription start site (TSS) of P3 is located 78 nucleotides downstream of the previously reported TSS. Subsequently, the P3 promoter sequence was identified and validated by mutagenesis analyses. Deletion of the saePQ region including the P1 promoter did not significantly alter the expression patterns of coagulase and alpha-hemolysin, two well-known sae target genes. Due to its L18P substitution in a transmembrane domain, SaeS in strain Newman has a constitutive kinase activity. Interestingly, the mutation also rendered the protein unstable, but the protein stability was restored by SaeQ, suggesting a possible SaeQ-SaeS interaction. Ironically, the same mutation seems to increase mRNA stability. SaeR appears to be stabilized by SaeS, possibly by a protein-protein interaction. Chromosomal mutation of P1 did not affect the expression pattern of coagulase and alpha-hemolysin. Based on these results, we conclude that transcription of saeRS from P3 is sufficient for target gene activation and that P1 is not involved in the activation.