Mutations targeting the plug‐domain of the Shewanella oneidensis proton‐driven stator allow swimming at increased viscosity and under anaerobic conditions
Mutations targeting the plug‐domain of the Shewanella oneidensis proton‐driven stator allow swimming at increased viscosity and under anaerobic conditions
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DOI：
10.1111/mmi.13499
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发表时间：
2016-12
影响因子：
3.6
通讯作者：
Susanne Brenzinger;L. Dewenter;Nicolas Delalez;Oliver Leicht;Volker Berndt;A. Paulick;R. Berry;M. Thanbichler;J. Armitage;Berenike Maier;K. Thormann
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文献类型：
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作者：
Susanne Brenzinger;L. Dewenter;Nicolas Delalez;Oliver Leicht;Volker Berndt;A. Paulick;R. Berry;M. Thanbichler;J. Armitage;Berenike Maier;K. Thormann
希瓦氏菌MR-1具有两个不同的定子单元来驱动鞭毛旋转，Na+依赖的PomAB定子和H+驱动的MotAB定子，后者可能通过侧向基因转移获得。虽然两个定子都可以独立驱动游泳通过液体，但MotAB驱动的电机无法支持结构化环境中的有效运动或厌氧条件下的游泳。使用ΔpomAB细胞，我们分离了能够通过软琼脂移动的自发突变体。我们发现，一个突变，改变了MotB的插头结构域的结构，影响运动功能，并允许细胞游泳通过介质的粘度增加，在厌氧条件下。转子周围的突变定子的数量和交换率与野生型定子没有显著差异，这表明定子的数量不是游泳效率增加的原因。非质子突变MotAB驱动细胞的游泳速度降低，其中一些定子的过表达导致生长速率降低，这意味着不与转子接合的突变定子允许一些质子泄漏。结果表明，MotB插头域中的突变改变了质子与定子离子通道的相互作用的方式，既增加扭矩输出，并允许游泳在降低的pmf值。
Shewanella oneidensis MR‐1 possesses two different stator units to drive flagellar rotation, the Na+‐dependent PomAB stator and the H+‐driven MotAB stator, the latter possibly acquired by lateral gene transfer. Although either stator can independently drive swimming through liquid, MotAB‐driven motors cannot support efficient motility in structured environments or swimming under anaerobic conditions. Using ΔpomAB cells we isolated spontaneous mutants able to move through soft agar. We show that a mutation that alters the structure of the plug domain in MotB affects motor functions and allows cells to swim through media of increased viscosity and under anaerobic conditions. The number and exchange rates of the mutant stator around the rotor were not significantly different from wild‐type stators, suggesting that the number of stators engaged is not the cause of increased swimming efficiency. The swimming speeds of planktonic mutant MotAB‐driven cells was reduced, and overexpression of some of these stators caused reduced growth rates, implying that mutant stators not engaged with the rotor allow some proton leakage. The results suggest that the mutations in the MotB plug domain alter the proton interactions with the stator ion channel in a way that both increases torque output and allows swimming at decreased pmf values.