Johnson M S, Rowsell E H, Taylor B L
Department of Microbiology and Molecular Genetics, Loma Linda University, CA 92350, USA.
FEBS Lett. 1995 Oct 30;374(2):161-4. doi: 10.1016/0014-5793(95)01097-x.
Transphosphorylation between the chemotaxis proteins and phosphoenolpyruvate:sugar phosphotransferase system (PTS) from Escherichia coli was investigated by incubating the CheA, CheW and CheY proteins of the chemotaxis cascade, and Enzyme I, HPr and Enzyme IImtl of the PTS with [gamma-32P]ATP or [32P]phosphoenolpyruvate in the presence and absence of cell extract. In the absence of cell extract, ATP phosphorylated CheA, but in the presence of cell extract, Enzyme I was also phosphorylated. Phosphoenolpyruvate phosphorylated only PTS components. The transphosphorylation of Enzyme I by ATP did not require chemotaxis proteins, and likely occurred through acetate kinase. Regardless of phosphorylation state, the HPr protein did not inhibit the rate of ATP-dependent phosphorylation of the CheA or the CheY protein. It is concluded that chemotaxis to PTS substrates is not mediated by transphosphorylation between the PTS and chemotaxis systems.
通过在有无细胞提取物的情况下，将趋化级联反应的CheA、CheW和CheY蛋白以及磷酸烯醇丙酮酸：糖磷酸转移酶系统（PTS）的酶I、HPr和酶IImtl与[γ-32P]ATP或[32P]磷酸烯醇丙酮酸一起孵育，研究了来自大肠杆菌的趋化蛋白与磷酸烯醇丙酮酸：糖磷酸转移酶系统（PTS）之间的转磷酸化作用。在没有细胞提取物的情况下，ATP使CheA磷酸化，但在有细胞提取物的情况下，酶I也被磷酸化。磷酸烯醇丙酮酸仅使PTS组分磷酸化。ATP对酶I的转磷酸化不需要趋化蛋白，可能是通过乙酸激酶发生的。无论磷酸化状态如何，HPr蛋白均不抑制CheA或CheY蛋白的ATP依赖性磷酸化速率。得出的结论是，对PTS底物的趋化作用不是由PTS和趋化系统之间的转磷酸化介导的。
