CONSERVED ASPARTATE RESIDUES AND PHOSPHORYLATION IN SIGNAL TRANSDUCTION BY THE CHEMOTAXIS PROTEIN CHEY
CONSERVED ASPARTATE RESIDUES AND PHOSPHORYLATION IN SIGNAL TRANSDUCTION BY THE CHEMOTAXIS PROTEIN CHEY
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DOI：
10.1073/pnas.87.1.41
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发表时间：
1990-01-01
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：
BOURRET, RB;HESS, JF;SIMON, MI
在大肠杆菌中，CheY蛋白被CheA磷酸化并被CheZ去磷酸化，作为趋化信号转导途径的一部分。已经提出CheY的磷酸化发生在天冬氨酸残基上。通过使用定点诱变来替换CheY的八个天冬氨酸残基中的每一个。在Asp-11、Asp-13或Asp-57处的取代导致趋化性丧失。大多数的突变体CheY蛋白仍然磷酸化的CheA，但表现出修改的生化特性，包括降低的能力，接受磷酸从CheA，改变磷酸基团的稳定性，和/或抗CheZ介导的去磷酸化。在位置57处具有取代的CheY蛋白的性质是最异常的，与Asp-57是酰基磷酸形成的正常位点的假设一致。在Asp-57突变体的磷酸化的替代网站的证据。磷酸化的CheY被认为会导致翻滚行为。然而，一个显性突变体CheY蛋白，不磷酸化在体外引起翻滚在体内不存在的CheA。这种表型表明磷酸化在野生型CheY蛋白中的作用是稳定可产生翻滚行为的瞬时构象变化。
The CheY protein is phosphorylated by CheA and dephosphorylated by CheZ as part of the chemotactic signal transduction pathway In Escherichia coli. Phosphorylation of CheY has been proposed to occur on an aspartate residue. Each of the eight aspartate residues of CheY was replaced by using site-directed mutagenesis. Substitutions at Asp-11, Asp-13, or Asp-57 resulted in loss of chemotaxis. Most of the mutant CheY proteins were still phosphorylated by CheA but exhibited modified biochemical properties, including reduced ability to accept phosphate from CheA, altered phosphate group stability, and/or resistance to CheZ-mediated dephosphorylation. The properties of CheY proteins bearing a substitution at position 57 were most aberrant, consistent with the hypothesis that Asp-57 is the normal site of acyl phosphate formation. Evidence for an alternate site of phosphorylation in the Asp-57 mutants is presented. Phosphorylated CheY is believed to cause tumbling behavior. However, a dominant mutant CheY protein that was not phosphorylated in vitro caused tumbling in vivo in the absence of CheA. This phenotype suggests that the role of phosphorylation in the wild-type CheY protein is to stabilize a transient conformational change that can generate tumbling behavior.