Proteins of Functioning Flagellar Rotor Turnover but only in the Presence of Signalling Proteins
Proteins of Functioning Flagellar Rotor Turnover but only in the Presence of Signalling Proteins
复制标题
具有功能的鞭毛转子转换的蛋白质，但仅在信号蛋白存在的情况下
DOI：
10.1016/j.bpj.2009.12.2350
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发表时间：
2010
影响因子：
3.4
通讯作者：
Delalez N
中科院分区：
文献类型：
--
作者：
Delalez N
对于许多细菌来说，运动性是通过一个或多个细丝来实现的，每个细丝由嵌入细胞膜中的旋转马达驱动。细菌鞭毛旋转马达是自然界最复杂的分子机器之一，由两个主要部分组成：转子和定子。虽然人们对它的静态结构了解很多，但在自然条件下活细胞中其成分的动态和相互作用的数据很少。最近的研究结果表明，跨膜蛋白复合物MotAB定位在转子周围并形成扭矩产生单元，从而进行快速交换。C环，也称为“开关复合物”，是转子的一部分，位于马达的细胞质区域。反应调节剂CheY-P结合的C环组件之一，FliM，导致转子切换旋转方向，从而使FliM的接口与chemosensory pathway.在这里，我们使用单分子荧光成像在大肠杆菌细胞表达基因组编码的YPet衍生物的FliM在生理水平。功能鞭毛马达的分析显示，每个包含1034个FliM分子。我们发现，两个FliM种群共存于同一个电机，一个不断营业额和一个保持“固定”。令人惊讶的是，动态群体内的交换依赖于反应调节蛋白的存在，该蛋白将复合物连接到感觉通路的其余部分，因此可能在细胞内的信号处理中发挥积极作用。
For many bacteria, motility is achieved by means of one or more filaments, each being driven by a rotary motor embedded in the cell membrane. The bacterial flagellar rotary motor is one of nature's most intricate molecular machines and is composed of two main parts: the rotor and the stator. Whilst much is known about its static structure, there are little data on the dynamics and interactions of its constituents under natural conditions in living cells. Recent results revealed the rapid exchange undergone by the membrane spanning protein complex MotAB which localizes around the rotor and forms the torque generating units. The C-ring, also called “switch complex”, is part of the rotor and is localized to the cytoplasmic region of the motor. The response regulator CheY-P binds one of the C-ring components, FliM, causing the rotor to switch rotational direction thus making FliM the interface with the chemosensory pathway.Here, we use single-molecule fluorescence imaging in Escherichia coli cells expressing genomically-encoded YPet derivatives of FliM at physiological levels. Analysis of functional flagellar motors revealed that each contains∼ 34 FliM molecules. We found that two FliM populations coexist within the same motor, one undergoing constant turnover and one remaining “fixed”. Surprisingly, exchange within the dynamic population relies on the presence of the response regulator protein linking the complex to the rest of the sensory pathway and may therefore play an active part of signal processing within the cell.