The Helix Rearrangement in the Periplasmic Domain of the Flagellar Stator B Subunit Activates Peptidoglycan Binding and Ion Influx
The Helix Rearrangement in the Periplasmic Domain of the Flagellar Stator B Subunit Activates Peptidoglycan Binding and Ion Influx
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DOI：
10.1016/j.str.2018.02.016
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发表时间：
2018-04-03
期刊：
影响因子：
5.7
通讯作者：
Imada, Katsumi
中科院分区：
文献类型：
--
作者：
Kojima, Seiji;Takao, Masato;Imada, Katsumi
细菌鞭毛马达的定子将离子流与扭矩产生耦合。离子传导定子通道仅在通过B亚基的肽聚糖（PG）结合结构域（MotB（C））并入转子并锚定在转子周围时打开。然而，没有直接证据表明PG结合与通道激活耦合。在这里，我们报告的MotBC负责这个耦合过程的结构重排。具有L119 P置换的MotB（C）片段（已知其引起通道活化）能够结合PG。MotB（C）的核磁共振分析和MotB（C）-L119 P二聚体的晶体结构揭示了螺旋α 1中的主要结构变化。体内交联结果证实发生了主要重排。我们的研究结果表明，定子纳入电机，螺旋α 1 MotB（C）的变化成一个扩展的非螺旋结构。我们认为这种变化允许定子结合PG并打开其质子通道。
The stator of the bacterial flagellar motor couples ion flow with torque generation. The ion-conducting stator channel opens only when incorporated into and anchored around the rotor via the peptidoglycan (PG) binding domain of the B subunit (MotB(C)). However, no direct evidence of PG binding coupled with channel activation has been presented. Here, we report the structural rearrangements of MotBC responsible for this coupling process. A MotB(C) fragment with the L119P replacement, which is known to cause channel activation, was able to bind PG. Nuclear magnetic resonance analysis of MotB(C) and the crystal structure of the MotB(C)-L119P dimer revealed major structural changes in helix alpha 1. In vivo crosslinking results confirm that a major rearrangement occurs. Our results suggest that, upon stator incorporation into the motor, helix alpha 1 of MotB(C) changes into an extended non-helical structure. We propose that this change allows the stator both to bind PG and to open its proton channel.