The bacterial flagellar switch complex is getting more complex
The bacterial flagellar switch complex is getting more complex
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DOI：
10.1038/emboj.2008.48
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发表时间：
2008-04-09
期刊：
影响因子：
11.4
通讯作者：
Eisenbach, Michael
中科院分区：
文献类型：
--
作者：
Cohen-Ben-Lulu, Galit N.;Francis, Noreen R.;Eisenbach, Michael
细菌鞭毛开关决定了鞭毛旋转的方向，对趋化性至关重要，其功能机制多年来一直是一个谜。在这里，我们发现开关复合物与膜结合呼吸蛋白富马酸还原酶（FRD）相关。我们提供的证据表明，FRD与分离的开关复合物结合，与开关蛋白FliG形成1:1的复合物，并且这种相互作用是鞭毛组装和切换鞭毛旋转方向所必需的。我们进一步表明富马酸，已知是一个顺时针/开关因子，通过FRD影响鞭毛旋转的方向。这些结果不仅揭示了对开关和鞭毛组装重要的新成分，而且还揭示了FRD，一种已知主要在大肠杆菌厌氧条件下表达和发挥作用的酶，在有氧条件下具有重要的，意想不到的功能。
The mechanism of function of the bacterial flagellar switch, which determines the direction of flagellar rotation and is essential for chemotaxis, has remained an enigma for many years. Here we show that the switch complex associates with the membrane-bound respiratory protein fumarate reductase (FRD). We provide evidence that FRD binds to preparations of isolated switch complexes, forms a 1:1 complex with the switch protein FliG, and that this interaction is required for both flagellar assembly and switching the direction of flagellar rotation. We further show that fumarate, known to be a clockwise/switch factor, affects the direction of flagellar rotation through FRD. These results not only uncover a new component important for switching and flagellar assembly, but they also reveal that FRD, an enzyme known to be primarily expressed and functional under anaerobic conditions in Escherichia coli, nonetheless, has important, unexpected functions under aerobic conditions.