The short form of CheA couples chemoreception to CheA phosphorylation.
The short form of CheA couples chemoreception to CheA phosphorylation.
复制标题
CheA 的缩写形式将化学感受与 CheA 磷酸化结合起来。
DOI：
10.1128/jb.176.15.4483-4491.1994
复制
发表时间：
1994
影响因子：
3.2
通讯作者：
Stewart,RC
中科院分区：
文献类型：
--
作者：
Wolfe,AJ;McNamara,BP;Stewart,RC
大肠杆菌细胞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在趋化信号转导中起着至关重要的作用。作为一种组氨酸蛋白激酶，它首先在氨基酸His-48处自磷酸化，然后磷酸化另外两种趋化蛋白CheY和切布。短型CheAS缺少CheAL的氨基末端97个氨基酸，因此不含自磷酸化位点。然而，它确实保留了功能性激酶结构域。因此，CheAS可以介导激酶缺陷型CheAL变体的转磷酸化。在这里，我们证明在体外，CheAS也可以介导转磷酸化的CheAL变体，缺乏C-末端片段，一部分的蛋白质，被认为是相互作用的CheW和化学感受器。Chew和化学感受器Tsr的存在增强了这种活性，并导致响应Tsr配体L-丝氨酸的转磷酸化速率的调节。因为CheAS可以介导这种活性，所以它可以恢复表达这种截短的CheAL变体的大肠杆菌细胞的趋化能力。
Escherichia coli cells express 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 chemotactic signal transduction. As a histidine protein kinase, it first autophosphorylates at amino acid His-48; then, it phosphorylates two other chemotaxis proteins, CheY and CheB. The short form, CheAS, lacks the amino-terminal 97 amino acids of CheAL and, therefore, does not contain the site of autophosphorylation. However, it does retain a functional kinase domain. As a consequence, CheAS can mediate transphosphorylation of kinase-deficient CheAL variants. Here we demonstrate in vitro that CheAS also can mediate transphosphorylation of a CheAL variant that lacks the C-terminal segment, a portion of the protein which is thought to interact with CheW and the chemoreceptors. The presence of CheW and the chemoreceptor Tsr enhances this activity and results in modulation of the transphosphorylation rate in response to the Tsr ligand, L-serine. Because CheAS can mediate this activity, it can restore chemotactic ability to Escherichia coli cells that express this truncated CheAL variant.