TRANSMEMBRANE SIGNAL TRANSDUCTION IN BACTERIAL CHEMOTAXIS INVOLVES LIGAND-DEPENDENT ACTIVATION OF PHOSPHATE GROUP TRANSFER
TRANSMEMBRANE SIGNAL TRANSDUCTION IN BACTERIAL CHEMOTAXIS INVOLVES LIGAND-DEPENDENT ACTIVATION OF PHOSPHATE GROUP TRANSFER
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DOI：
10.1073/pnas.86.4.1208
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发表时间：
1989-02-01
影响因子：
11.1
通讯作者：
SIMON, MI
中科院分区：
文献类型：
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作者：
BORKOVICH, KA;KAPLAN, N;SIMON, MI
大肠杆菌的信号转导涉及跨膜受体蛋白（如天冬氨酸受体、Tar）和四种趋化基因（cheA、cheY、cheW和cheZ）的产物之间的相互作用。先前的研究表明，cheA基因产物是一种自磷酸化蛋白激酶，可将磷酸盐转移到CheY，而cheZ基因产物则是一种特定的CheY磷酸酶。在这里，我们报道了该系统可以在体外重建，受体功能可以耦合到CheY磷酸化。偶联需要存在CheW蛋白、受体的适当形式以及CheA和CheY蛋白。在这些条件下，CheY-phosphate的积累增强。300倍。在使用野生型和‘’‘’翻滚‘’‘’突变受体而不是‘’‘’平滑‘’‘’突变受体的反应中可以看到这种速率增强。微摩尔浓度的天冬氨酸抑制了磷蛋白积累的增加，使用野生型受体，而不是tumble型受体。这些结果提供了证据，表明细菌趋化的信号转导途径涉及受体介导的磷酸化蛋白水平的改变。他们认为CheW是受体和磷酸化之间的偶联因子。结果也支持了CheY-phosphate是翻滚信号的建议。
Signal transduction in Escherichia coli involves the interaction of transmembrane receptor proteins such as the aspartate receptor, Tar, and the products of four chemotaxis genes, cheA, cheY, cheW, and cheZ. It was previously shown that the cheA gene product is an autophosphorylating protein kinase that transfers phosphate to CheY, whereas the cheZ gene product acts as a specific CheY phosphatase. Here we report that the system can be reconstituted in vitro and receptor function can be coupled to CheY phosphorylation. Coupling requires the presence of the CheW protein, the appropriate form of the receptor, and the CheA and CheY proteins. Under these conditions the accumulation of CheY-phosphate is enhanced .apprxeq. 300-fold. This rate enhancement is seen in reactions using wild-type and ''''tumble'''' mutant receptors but not ''''smooth'''' mutant receptors. The increased accumulation of phosphoprotein was inhibited by micromolar concentrations of aspartate, using wild-type, but not tumble, receptors. These results provide evidence that the signal transduction pathway in bacterial chemotaxis involves receptor-mediated alteration of the levels of phosphorylated proteins. They suggest that CheW acts as the coupling factor between receptor and phosphorylation. The results also support the suggestion that CheY-phosphate is the tumble signal.