Stator assembly and activation mechanism of the flagellar motor by the periplasmic region of MotB
Stator assembly and activation mechanism of the flagellar motor by the periplasmic region of MotB
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DOI：
10.1111/j.1365-2958.2009.06802.x
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发表时间：
2009-08-01
影响因子：
3.6
通讯作者：
Namba, Keiichi
中科院分区：
文献类型：
--
作者：
Kojima, Seiji;Imada, Katsumi;Namba, Keiichi
沙门氏菌鞭毛马达中的扭矩产生与H+离子通过Mot蛋白定子复合体的质子传导通道的转移相耦合。Mot复合体被认为是通过MOTB的肽聚糖结合(PGB)结构域锚定在肽聚糖(PG)层上的。只有当定子安装到电机中时，质子转移才被激活。我们报道了MOTB的C-末端周质片段(MotBC)的晶体结构，它包含PGB结构域，并包括对运动至关重要的整个周质区域。结构和功能分析表明，PGB结构域必须二聚化才能形成质子传导通道。无论是PG结合还是质子通道激活，MotBC的N末端都需要发生剧烈的构象变化。
Torque generation in the Salmonella flagellar motor is coupled to translocation of H+ ions through the proton-conducting channel of the Mot protein stator complex. The Mot complex is believed to be anchored to the peptidoglycan (PG) layer by the putative peptidoglycan-binding (PGB) domain of MotB. Proton translocation is activated only when the stator is installed into the motor. We report the crystal structure of a C-terminal periplasmic fragment of MotB (MotBC) that contains the PGB domain and includes the entire periplasmic region essential for motility. Structural and functional analyses indicate that the PGB domains must dimerize in order to form the proton-conducting channel. Drastic conformational changes in the N-terminal portion of MotBC are required both for PG binding and the proton channel activation.