Ozturk Gulustan, LeGrand Karen, Zheng Yan, Young Glenn M
Department of Food Science and Technology, University of California, One Shields Avenue, Davis, CA 95616-8598, USA.
College of Food Science, Shenyang Agricultural University, No. 120 Dongling Road, Shenhe District, Shenyang, Liaoning Province, 110866, P. R. China.
FEMS Microbiol Lett. 2017 Nov 1;364(20). doi: 10.1093/femsle/fnx204.
This study investigated how carbon storage regulator A (CsrA) affects expression of the Ysa and Ysc type 3 secretion (T3S) system genetic regulatory cascades that control Ysps (Yersinia secreted proteins) and Yops (Yersinia outer proteins) export, respectively. Given that most often CsrA acts as a mediator of mRNA stability, an activity that can be monitored using lacZ transcriptional fusions, we employed a collection of reporter strains to assess Ysa and Ysc gene expression. To this end, bacteria were cultivated to induce either the Ysa or the Ysc T3S system. Comparison of csrA mutants to the wild-type strain revealed that, in response to the respective inducing conditions, genes spanning the Ysa and Ysc gene cascades displayed increased expressions. Then, the possibility that CsrA affects secretion of Ysps and Yops was tested and the profiles of secreted proteins by wild-type and csrA mutant strains were compared by proteomic analysis. Ysps were over-secreted and Yops were under-secreted, for the csrA mutant. These results support the hypothesis that CsrA affects both the Ysa and Ysc T3S systems in Yersinia enterocolitica. They further support the conclusion that CsrA plays an important role in controlling adaptation of this pathogenic bacterium during its lifecycle shift between a terrestrial and parasitic existence.
本研究调查了碳储存调节因子A（CsrA）如何影响Ysa和Ysc Ⅲ型分泌（T3S）系统的遗传调控级联反应，这两个调控级联反应分别控制耶尔森菌分泌蛋白（Ysps）和耶尔森菌外膜蛋白（Yops）的输出。鉴于CsrA通常作为mRNA稳定性的调节因子，其活性可用lacZ转录融合来监测，我们使用了一系列报告菌株来评估Ysa和Ysc基因的表达。为此，培养细菌以诱导Ysa或Ysc T3S系统。将csrA突变体与野生型菌株进行比较，结果显示，在各自的诱导条件下，Ysa和Ysc基因级联反应中的基因表达均增加。然后，测试了CsrA影响Ysps和Yops分泌的可能性，并通过蛋白质组学分析比较了野生型和csrA突变体菌株的分泌蛋白谱。对于csrA突变体，Ysps分泌过量而Yops分泌不足。这些结果支持了CsrA影响小肠结肠炎耶尔森菌中Ysa和Ysc T3S系统的假说。它们进一步支持了CsrA在控制这种病原菌在陆地生存和寄生生存之间生命周期转变过程中的适应性方面发挥重要作用的结论。
