The mobility of two kinase domains in the Escherichia coli chemoreceptor array varies with signalling state.
The mobility of two kinase domains in the Escherichia coli chemoreceptor array varies with signalling state.
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DOI：
10.1111/mmi.12309
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发表时间：
2013-09
影响因子：
3.6
通讯作者：
Jensen GJ
中科院分区：
文献类型：
--
作者：
Briegel A;Ames P;Gumbart JC;Oikonomou CM;Parkinson JS;Jensen GJ
能动细菌通过高度合作的、有序的化学感受器阵列来感知它们的物理和化学环境。这些信号复合物磷酸化一种反应调节剂，该调节剂反过来控制鞭毛运动逆转，将细胞推向有利的环境。将化学效应物结合转化为适当激酶输出的结构变化尚不清楚。在这里，我们应用高分辨率电子冷冻断层扫描可视化突变的化学感受器信号阵列在明确定义的激酶活性状态。阵列在所有信号传导状态下都是有序的，在2-3 nm分辨率下受体构象没有可辨别的差异。然而，在龙骨状密度中观察到差异，我们在这里将其确定为CheA激酶结构域P1和P2，它们分别是磷酸化位点结构域和反应调节靶蛋白的结合结构域。具有高激酶活性的突变体受体阵列都表现出小龙骨和高蛋白水解敏感性，表明移动的P1和P2结构域。相比之下，在激酶关闭信号状态下的阵列表现出一系列的龙骨尺寸。这些研究结果证实，化学感受器阵列在信号传导过程中不会发生大的结构变化，相反，表明激酶活性至少部分由关键结构域的流动性变化来调节。
Motile bacteria sense their physical and chemical environment through highly cooperative, ordered arrays of chemoreceptors. These signaling complexes phosphorylate a response regulator which in turn governs flagellar motor reversals, driving cells towards favorable environments. The structural changes that translate chemoeffector binding into the appropriate kinase output are not known. Here, we apply high-resolution electron cryotomography to visualize mutant chemoreceptor signaling arrays in well-defined kinase activity states. The arrays were well ordered in all signaling states, with no discernible differences in receptor conformation at 2-3 nm resolution. Differences were observed, however, in a keel-like density that we identify here as CheA kinase domains P1 and P2, which are the phosphorylation site domain and the binding domain for response regulator target proteins, respectively. Mutant receptor arrays with high kinase activities all exhibited small keels and high proteolysis susceptibility, indicative of mobile P1 and P2 domains. In contrast, arrays in kinase-off signaling states exhibited a range of keel sizes. These findings confirm that chemoreceptor arrays do not undergo large structural changes during signaling, and suggest instead that kinase activity is modulated at least in part by changes in the mobility of key domains.
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作者：
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DOI：
10.1073/pnas.1115719109
发表时间：
2012-03-06
影响因子：
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作者：
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