Glucose-Specific Enzyme IIA of the Phosphoenolpyruvate:Carbohydrate Phosphotransferase System Modulates Chitin Signaling Pathways in Vibrio cholerae
Glucose-Specific Enzyme IIA of the Phosphoenolpyruvate:Carbohydrate Phosphotransferase System Modulates Chitin Signaling Pathways in Vibrio cholerae
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DOI：
10.1128/jb.00127-17
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发表时间：
2017-05
影响因子：
3.2
通讯作者：
Shouji Yamamoto;M. Ohnishi
中科院分区：
文献类型：
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作者：
Shouji Yamamoto;M. Ohnishi
在霍乱弧菌中，几丁质利用和天然感受态所需的基因由几丁质反应双组分系统（TCS）传感器激酶ChiS控制。在经典的TCS范例中，传感器激酶特异性磷酸化同源反应调节因子以激活基因表达。然而，我们先前的遗传研究表明，ChiS通过使用不同于经典磷酸化反应的机制刺激非TCS转录调节因子TfoS（S. Yamamoto，J. Mitobe，T.石川、S. N.阿威，M. Ohnishi，H. Watanabe和H. Izumiya，Mol Microbiol 91：326-347，2014，https://doi.org/10.1111/mmi.12462）。TfoS特异性激活tfoR的转录，编码感受态基因表达所必需的小调控RNA。ChiS和TfoS是否直接相互作用仍然未知。为了确定是否有其他因素介导ChiS和TfoS之间的通讯，我们分离了关闭tfoR：：lacZ表达但拥有完整的ChiS和tfoS基因的转座子突变体。我们证明了一个意想不到的关联几丁质诱导的信号通路与葡萄糖特异性酶IIA（EIIAglc）的磷酸烯醇丙酮酸：碳水化合物磷酸转移酶系统（PTS）的碳水化合物的摄取和分解代谢物控制的基因表达。遗传和生理分析表明，去磷酸化的EIIAglc失活的自然能力和tfoR转录。几丁质诱导的表达的chb操纵子，这是所需的几丁质运输和catalysts，也被抑制去磷酸化EIAglc。此外，调节tfoR和chb的表达EIIAglc依赖于ChiS和胞内水平的ChiS不受破坏的基因编码EIIAglc。这些结果定义了以前未知的PTS和几丁质信号通路之间的连接在霍乱弧菌，并提出了一种策略，使这种细菌可以在生理上适应现有的营养状况。PTS的EIIAglc蛋白协调多种生理功能与碳可用性。在这份报告中，我们描述了一个意想不到的协会几丁质激活的信号通路在V. cholesterol与EIIAglc。信号传导途径由几丁质响应性TCS传感器激酶ChiS控制，并导致几丁质利用和天然感受态的诱导。我们发现，去磷酸化的EIIAglc抑制这两个信号通路中的ChiS依赖性的方式。这种抑制作用不同于由环AMP水平降低引起的经典分解代谢物阻遏。这项工作代表了一个新发现的PTS和几丁质信号通路之间的连接在V. cholesterol，并提出了一种策略，使这种细菌可以在生理上适应现有的营养状况。
ABSTRACT In Vibrio cholerae, the genes required for chitin utilization and natural competence are governed by the chitin-responsive two-component system (TCS) sensor kinase ChiS. In the classical TCS paradigm, a sensor kinase specifically phosphorylates a cognate response regulator to activate gene expression. However, our previous genetic study suggested that ChiS stimulates the non-TCS transcriptional regulator TfoS by using mechanisms distinct from classical phosphorylation reactions (S. Yamamoto, J. Mitobe, T. Ishikawa, S. N. Wai, M. Ohnishi, H. Watanabe, and H. Izumiya, Mol Microbiol 91:326–347, 2014, https://doi.org/10.1111/mmi.12462 ). TfoS specifically activates the transcription of tfoR, encoding a small regulatory RNA essential for competence gene expression. Whether ChiS and TfoS interact directly remains unknown. To determine if other factors mediate the communication between ChiS and TfoS, we isolated transposon mutants that turned off tfoR::lacZ expression but possessed intact chiS and tfoS genes. We demonstrated an unexpected association of chitin-induced signaling pathways with the glucose-specific enzyme IIA (EIIAglc) of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) for carbohydrate uptake and catabolite control of gene expression. Genetic and physiological analyses revealed that dephosphorylated EIIAglc inactivated natural competence and tfoR transcription. Chitin-induced expression of the chb operon, which is required for chitin transport and catabolism, was also repressed by dephosphorylated EIIAglc. Furthermore, the regulation of tfoR and chb expression by EIIAglc was dependent on ChiS and intracellular levels of ChiS were not affected by disruption of the gene encoding EIIAglc. These results define a previously unknown connection between the PTS and chitin signaling pathways in V. cholerae and suggest a strategy whereby this bacterium can physiologically adapt to the existing nutrient status. IMPORTANCE The EIIAglc protein of the PTS coordinates a wide variety of physiological functions with carbon availability. In this report, we describe an unexpected association of chitin-activated signaling pathways in V. cholerae with EIIAglc. The signaling pathways are governed by the chitin-responsive TCS sensor kinase ChiS and lead to the induction of chitin utilization and natural competence. We show that dephosphorylated EIIAglc inhibits both signaling pathways in a ChiS-dependent manner. This inhibition is different from classical catabolite repression that is caused by lowered levels of cyclic AMP. This work represents a newly identified connection between the PTS and chitin signaling pathways in V. cholerae and suggests a strategy whereby this bacterium can physiologically adapt to the existing nutrient status.