INTERMOLECULAR COMPLEMENTATION OF THE KINASE-ACTIVITY OF CHEA
INTERMOLECULAR COMPLEMENTATION OF THE KINASE-ACTIVITY OF CHEA
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DOI：
10.1111/j.1365-2958.1993.tb01588.x
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发表时间：
1993-05-01
影响因子：
3.6
通讯作者：
SIMON, MI
中科院分区：
文献类型：
--
作者：
SWANSON, RV;BOURRET, RB;SIMON, MI
CheA 是一种二聚体自磷酸化蛋白激酶，在控制大肠杆菌趋化性的信号转导网络中发挥着关键作用。使用激酶和调节功能缺陷的突变蛋白分析自磷酸化反应。发现自磷酸化位点突变 (CheA48HQ) 或缺失 (CheA(S)) 的蛋白质能够磷酸化激酶缺陷型突变体 CheA470GK。该反应的动力学支持以下假设：自磷酸化是二聚体内反式磷酸化的结果。 CheA 的羧基末端部分先前被证明对于自磷酸化是可有可无的，但需要响应通过传感器和 CheW 传输的环境信号进行调节。 CheA48HQ 或 CheA470GK 与缺乏该调节结构域的截短蛋白的混合表明，受调节的自磷酸化需要 CheA 二聚体中存在两个羧基末端部分。这些结果表明 CheA 的二聚体形式在细菌趋化性的信号转导中发挥着不可或缺的作用。
CheA is a dimeric autophosphorylating protein kinase that plays a critical role in the signal transduction network controlling chemotaxis in Escherichia coli. The autophosphorylation reaction was analysed using mutant proteins defective in kinase and regulatory functions. Proteins in which the site of autophosphorylation was mutated (CheA48HQ) or missing (CheA(S)) were found to phosphorylate the kinase-defective mutant, CheA470GK. The kinetics of this reaction support the hypothesis that autophosphorylation is the result of trans-phosphorylation within a dimer. The carboxy-terminal portion of CheA was previously shown to be dispensable for autophosphorylation, but required for regulation in response to environmental signals transmitted through a transducer and CheW. Mixing of CheA48HQ or CheA470GK with a truncated protein lacking this regulatory domain demonstrated that regulated autophosphorylation requires the presence of both carboxy-terminal portions in a CheA dimer. These results indicate that the dimeric form of CheA plays an integral role in signal transduction in bacterial chemotaxis.