The short form of the CheA protein restores kinase activity and chemotactic ability to kinase-deficient mutants.
The short form of the CheA protein restores kinase activity and chemotactic ability to kinase-deficient mutants.
复制标题
CheA 蛋白的短形式可恢复激酶缺陷突变体的激酶活性和趋化能力。
DOI：
10.1073/pnas.90.4.1518
复制
发表时间：
1993
影响因子：
11.1
通讯作者：
Stewart,RC
中科院分区：
文献类型：
--
作者：
Wolfe,AJ;Stewart,RC
大肠杆菌表达两种形式的趋化相关的CheA蛋白，CheAL和CheAS，作为在基因cheA中的两个不同的框内起始位点处的翻译起始的结果。长型CheAL通过磷酸化另外两种趋化蛋白：CheY和切布在趋化信号转导机制中起关键作用。CheAL必须首先在氨基酸His-48处自磷酸化，然后将其膦酰基转移到这些其他信号转导蛋白。短型CheAS缺少CheAL的N-末端97个氨基酸，因此不具有自磷酸化位点。在这里，我们证明，虽然它缺乏自磷酸化的能力，CheAS可以介导磷酸化的激酶缺陷的变体CheAL，其中每个保留一个功能性的自磷酸化位点。这种转磷酸化使这些激酶缺陷型CheAL变体能够磷酸化CheY。因为它介导这种活性，CheAS可以恢复到激酶缺陷的E。大肠杆菌细胞翻滚的能力，因此，在群板测定中执行趋化性。
Escherichia coli expresses two forms of the chemotaxis-associated CheA protein, CheAL and CheAS, as the result of translational initiation at two distinct, in-frame initiation sites in the gene cheA. The long form, CheAL, plays a crucial role in the chemotactic signal transduction mechanism by phosphorylating two other chemotaxis proteins: CheY and CheB. CheAL must first autophosphorylate at amino acid His-48 before transferring its phosphono group to these other signal transduction proteins. The short form, CheAS, lacks the N-terminal 97 amino acids of CheAL and, therefore, does not possess the site of autophosphorylation. Here we demonstrate that although it lacks the ability to autophosphorylate, CheAS can mediate phosphorylation of kinase-deficient variants of CheAL each of which retains a functional autophosphorylation site. This transphosphorylation enables these kinase-deficient CheAL variants to phosphorylate CheY. Because it mediates this activity, CheAS can restore to kinase-deficient E. coli cells the ability to tumble and, thus, to perform chemotaxis in swarm plate assays.