Gegner J A, Graham D R, Roth A F, Dahlquist F W
Institute of Molecular Biology, University of Oregon, Eugene 97403.
Cell. 1992 Sep 18;70(6):975-82. doi: 10.1016/0092-8674(92)90247-a.
We examined the binding interactions of the methylation-dependent chemotaxis receptors Tsr and Tar with the chemotaxis-specific protein kinase CheA and the coupling factor CheW. Receptor directly bound CheW, but receptor-CheA binding was dependent upon the presence of CheW. These observations in combination with our previous identification of a CheW-CheA complex suggest that CheW physically links the kinase to the receptor. The ternary complex of receptor, CheW, and CheA is both kinetically and thermodynamically stable at physiological concentrations. Stability is not significantly altered by changes associated with attractant or repellent binding to the receptor. Such binding greatly modulates the kinase activity of CheA. Our results demonstrate that modulation of the kinase activity does not require association-dissociation of the ternary complex. This suggests that the receptor signal is transduced through conformational changes in the ternary complex rather than through changes in the association of the kinase CheA with receptor and/or CheW.
我们研究了甲基化依赖性趋化受体Tsr和Tar与趋化特异性蛋白激酶CheA以及偶联因子CheW之间的结合相互作用。受体直接结合CheW，但受体与CheA的结合依赖于CheW的存在。这些观察结果与我们之前鉴定的CheW-CheA复合物相结合，表明CheW在物理上把激酶与受体连接起来。受体、CheW和CheA的三元复合物在生理浓度下在动力学和热力学上都是稳定的。与吸引剂或驱避剂与受体结合相关的变化不会显著改变其稳定性。这种结合极大地调节了CheA的激酶活性。我们的结果表明，激酶活性的调节并不需要三元复合物的缔合-解离。这表明受体信号是通过三元复合物的构象变化而不是通过激酶CheA与受体和/或CheW结合的变化来转导的。
