Control of direction of flagellar rotation in bacterial chemotaxis
Control of direction of flagellar rotation in bacterial chemotaxis
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DOI：
10.1073/pnas.95.1.201
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发表时间：
1998-01-06
影响因子：
11.1
通讯作者：
Berg, HC
中科院分区：
文献类型：
--
作者：
Scharf, BE;Fahrner, KA;Berg, HC
大肠杆菌的运动行为取决于其鞭毛马达的旋转方向。已知磷酸化信号分子 CheY 与运动组件 FliM 的结合可增强顺时针旋转。在体内研究这种相互作用很困难，因为 CheY 的激酶 CheA 磷酸化和 CheY 水解（由 CheZ 加速）的动力学不受直接实验控制。在这里，我们检查了双突变体 CheY(13DK106YW) 与鞭毛马达的相互作用，该双突变体 CheY(13DK106YW) 在没有磷酸化的情况下仍具有活性。行为测定是在缺乏 CheA 和 CheZ 的系留细胞上进行的。突变蛋白细胞内浓度变化的影响是高度非线性的。然而，它们可以通过热异构化模型来解释，其中顺时针和逆时针状态的自由能线性依赖于 CheY 结合的量。
The motile behavior of the bacterium Escherichia coli depends on the direction of rotation of its flagellar motors. Binding of the phosphorylated signaling molecule CheY to a motor component FliM is known to enhance clockwise rotation. It is difficult to study this interaction in vivo, because the dynamics of phosphorylation of CheY by its kinase CheA and the hydrolysis of CheY (accelerated by CheZ) are not under direct experimental control. Here, we examine instead the interaction with the flagellar motor of a double mutant CheY(13DK106YW) that is active without phosphorylation. The behavioral assays were carried out on tethered cells lacking CheA and CheZ. The effects of variation in intracellular concentration of the mutant protein were highly nonlinear. However, they can be explained by a thermal isomerization model in which the free energies of clockwise and counterclockwise states depend linearly on the amount of CheY bound.