Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel.
Mol Microbiol. 2010 May;76(4):932-43. doi: 10.1111/j.1365-2958.2010.07148.x. Epub 2010 Apr 13.
The ability of CheY, the response regulator of bacterial chemotaxis, to generate clockwise rotation is regulated by two covalent modifications - phosphorylation and acetylation. While the function and signal propagation of the former are widely understood, the mechanism and role of the latter are still obscure. To obtain information on the function of this acetylation, we non-enzymatically acetylated CheY to a level similar to that found in vivo, and examined its binding to its kinase CheA, its phosphatase CheZ and the switch protein FliM - its target at the flagellar switch complex. Acetylation repressed the binding to all three proteins. These results suggest that both phosphorylation and acetylation determine CheY's ability to bind to its target proteins, thus providing two levels of regulation, fast and slow respectively. The fast level is modulated by environmental signals (e.g. chemotactic and thermotactic stimuli). The slow one is regulated by the metabolic state of the cell and it determines, at each metabolic state, the fraction of CheY molecules that can participate in signalling.
细菌趋化性反应调节蛋白 CheY 的构象变化能力受两种共价修饰的调节：磷酸化和乙酰化。虽然前者的功能和信号转导机制已经被广泛了解，但后者的机制和作用仍然不清楚。为了获得关于这种乙酰化作用的功能信息，我们在非酶条件下将 CheY 乙酰化至类似于体内水平的程度，并检测了它与激酶 CheA、磷酸酶 CheZ 和鞭毛开关复合物中的开关蛋白 FliM 的结合情况。乙酰化抑制了与这三种蛋白的结合。这些结果表明，磷酸化和乙酰化都决定了 CheY 与靶蛋白结合的能力，从而提供了快速和缓慢两种调节水平。快速调节是由环境信号（如趋化性和热刺激）调节的。缓慢调节则由细胞的代谢状态决定，它决定了在每个代谢状态下，能够参与信号传递的 CheY 分子的比例。
