A slight bending of an α-helix in FliM creates a counterclockwise-locked structure of the flagellar motor in <i>Vibrio</i>
A slight bending of an α-helix in FliM creates a counterclockwise-locked structure of the flagellar motor in <i>Vibrio</i>
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FliM 中 α 螺旋的轻微弯曲在<i>Vibrio</i>中创建了鞭毛运动的逆时针锁定结构
DOI：
10.1093/jb/mvab074
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Imada Katsumi
中科院分区：
文献类型：
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作者：
Takekawa Norihiro;Nishikino Tatsuro;Yamashita Toshiki;Hori Kiyoshiro;Onoue Yasuhiro;Ihara Kunio;Kojima Seiji;Homma Michio;Imada Katsumi
许多细菌靠旋转的鞭毛游动。趋化系统控制鞭毛的旋转方向。溶藻弧菌有一个单极鞭毛，通过逆时针方向（CCW）旋转鞭毛马达来响应引诱剂，从而平稳地游动。响应于驱避剂，马达频繁地在CCW和顺时针（CW）之间切换其旋转方向。我们分离出一种突变株，它以CW锁定的鞭毛旋转方式游泳，这种旋转方式拉动而不是推动细胞。这种CW表型源于FliM中的R49 P取代，FliM是结合趋化性信号蛋白磷酸化CheY的马达C环中的组分。然而，这种表型是独立的CheY，表明突变产生的CW构象的C-环的CheY的情况下。R49 P取代的FliM的晶体结构显示FliM（FliMM）的中间结构域的N-末端α-螺旋的构象变化。该螺旋应介导FliM-FliM相互作用。野生型和突变型C环的结构模型表明，FliM中相对较小的构象变化引起FliM结构域构象的剧烈重排，产生C环的CW构象。
Many bacteria swim by rotating flagella. The chemotaxis system controls the direction of flagellar rotation.Vibrio alginolyticus, which has a single polar flagellum, swims smoothly by rotating the flagellar motor counterclockwise (CCW) in response to attractants. In response to repellents, the motor frequently switches its rotational direction between CCW and clockwise (CW). We isolated a mutant strain that swims with a CW-locked rotation of the flagellum, which pulls rather than pushes the cell. This CW phenotype arises from a R49P substitution in FliM, which is the component in the C-ring of the motor that binds the chemotaxis signalling protein, phosphorylated CheY. However, this phenotype is independent of CheY, indicating that the mutation produces a CW conformation of the C-ring in the absence of CheY. The crystal structure of FliM with the R49P substitution showed a conformational change in the N-terminal α-helix of the middle domain of FliM (FliMM). This helix should mediates FliM–FliM interaction. The structural models of wild type and mutant C-ring showed that the relatively small conformational change in FliMMinduces a drastic rearrangement of the conformation of the FliMMdomain that generates a CW conformation of the C-ring.