Contribution of Many Charged Residues at the Stator-Rotor Interface of the Na + -Driven Flagellar Motor to Torque Generation in Vibrio alginolyticus
Contribution of Many Charged Residues at the Stator-Rotor Interface of the Na + -Driven Flagellar Motor to Torque Generation in Vibrio alginolyticus
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DOI：
10.1128/jb.01392-13
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发表时间：
2014-04-01
影响因子：
3.2
通讯作者：
Homma, Michio
中科院分区：
文献类型：
--
作者：
Takekawa, Norihiro;Kojima, Seiji;Homma, Michio
在细菌鞭毛马达产生扭矩的过程中，MoTA和FliG在转子-定子界面的带电残基之间的静电相互作用是重要的。然而，这些带电残留物的实际作用(S)尚未得到澄清。在本研究中，我们系统地对溶藻弧菌进行了突变，将POMA(Mota Homologue)和FliG的荷电残基替换为无电荷残基或电荷反转残基，并对这些突变体的运动特性进行了研究。我们发现，一组带电残基的成员，POMA中的7个和FliG中的6个，共同参与了弧菌中Na(+)驱动的鞭毛马达的扭矩产生。POMA-E97和FliG-K284之间的额外特定相互作用对于弧菌电机的正常性能至关重要。我们的结果还表明，在弧菌Na(+)驱动的电机中，POMA-FliG相互作用中涉及的带电残基比在H(+)驱动的电机中参与Mota-FliG相互作用的电荷残基多。这表明，在Poma-FliG界面上大量保守的带电残基有助于弧菌发动机对突变的稳健性。Na(+)驱动的电机定子和转子的相互作用面似乎比以前提出的H(+)驱动电机的相互作用面更复杂。
In torque generation by the bacterial flagellar motor, it has been suggested that electrostatic interactions between charged residues of MotA and FliG at the rotor-stator interface are important. However, the actual role(s)of those charged residues has not yet been clarified. In this study, we systematically made mutants of Vibrio alginolyticus whose charged residues of PomA (MotA homologue) and FliG were replaced by uncharged or charge-reversed residues and characterized the motilities of those mutants. We found that the members of a group of charged residues, 7 in PomA and 6 in FliG, collectively participate in torque generation of the Na (+)- driven flagellar motor in Vibrio. An additional specific interaction between PomA-E97 and FliG-K284 is critical for proper performance of the Vibrio motor. Our results also reveal that more charged residues are involved in the PomA-FliG interactions in the Vibrio Na (+) -driven motor than in the MotA-FliG interactions in the H (+) -driven one. This suggests that a larger number of conserved charged residues at the PomA-FliG interface contributes to the robustness of the Vibrio motor against mutations. The interaction surfaces of the stator and rotor of the Na (+) -driven motor seem to be more complex than those previously proposed in the H (+) -driven motor.