Steiner Bradley D, Eberly Allison R, Hurst Melanie N, Zhang Ellisa W, Green Hamilton D, Behr Stefan, Jung Kirsten, Hadjifrangiskou Maria
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, USA.
Division of Molecular Pathogenesis, Department of Pathology, Microbiology & Immunology, Vanderbilt University Medical Center, 1161 21st Avenue South, MCN A5225A, Nashville, TN, 37232, USA.
J Membr Biol. 2018 Feb;251(1):65-74. doi: 10.1007/s00232-018-0014-2. Epub 2018 Jan 27.
Two-component systems (TCSs) dictate many bacterial responses to environmental change via the activation of a membrane-embedded sensor kinase, which has molecular specificity for a cognate response regulator protein. However, although the majority of TCSs operate through seemingly strict cognate protein-protein interactions, there have been several reports of TCSs that violate this classical model of signal transduction. Our group has recently demonstrated that some of these cross-interacting TCSs function in a manner that imparts a fitness advantage to bacterial pathogens. In this study, we describe interconnectivity between the metabolite-sensing TCSs YpdA/YpdB and BtsS/BtsR in uropathogenic Escherichia coli (UPEC). The YpdA/YpdB and BtsS/BtsR TCSs have been previously reported to interact in K12 E. coli, where they alter the expression of putative transporter genes yhjX and yjiY, respectively. These target genes are both upregulated in UPEC during acute and chronic murine models of urinary tract infection, as well as in response to pyruvate and serine added to growth media in vitro. Here, we show that proper regulation of yhjX in UPEC requires the presence of all components from both of these TCSs. By utilizing plasmid-encoded luciferase reporters tracking the activity of the yhjX and yjiY promoters, we demonstrate that deletions in one TCS substantially alter transcriptional activity of the opposing system's target gene. However, unlike in K12 E. coli, single gene deletions in the YpdA/YpdB system do not alter yjiY gene expression in UPEC, suggesting that niche and lifestyle-specific pressures may be selecting for differential cross-regulation of TCSs in pathogenic and non-pathogenic E. coli.
双组分系统（TCSs）通过激活膜嵌入的传感器激酶来决定许多细菌对环境变化的反应，该激酶对同源反应调节蛋白具有分子特异性。然而，尽管大多数双组分系统通过看似严格的同源蛋白质-蛋白质相互作用发挥作用，但已有几篇报道称双组分系统违反了这种经典的信号转导模型。我们小组最近证明，其中一些交叉相互作用的双组分系统以赋予细菌病原体适应性优势的方式发挥作用。在这项研究中，我们描述了尿路致病性大肠杆菌（UPEC）中代谢物感应双组分系统YpdA/YpdB和BtsS/BtsR之间的相互联系。先前报道YpdA/YpdB和BtsS/BtsR双组分系统在K12大肠杆菌中相互作用，在那里它们分别改变推定转运蛋白基因yhjX和yjiY的表达。在急性和慢性小鼠尿路感染模型中，以及在体外添加到生长培养基中的丙酮酸和丝氨酸的刺激下，这些靶基因在UPEC中均上调。在这里，我们表明UPEC中yhjX的正常调节需要这两个双组分系统的所有组分。通过利用追踪yhjX和yjiY启动子活性的质粒编码荧光素酶报告基因，我们证明一个双组分系统中的缺失会显著改变相对系统靶基因的转录活性。然而，与K12大肠杆菌不同，YpdA/YpdB系统中的单基因缺失不会改变UPEC中yjiY基因的表达，这表明生态位和生活方式特异性压力可能在选择致病性和非致病性大肠杆菌中双组分系统的差异交叉调节。
