Structural insights into the interaction between the bacterial flagellar motor proteins FliF and FliG.
Structural insights into the interaction between the bacterial flagellar motor proteins FliF and FliG.
复制标题
细菌鞭毛运动蛋白 FliF 和 FliG 之间相互作用的结构见解。
DOI：
10.1021/bi3004582
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发表时间：
2012
期刊：
影响因子：
2.9
通讯作者：
Dahlquist,FrederickW
中科院分区：
文献类型：
--
作者：
Levenson,Robert;Zhou,Hongjun;Dahlquist,FrederickW
可溶性细胞质蛋白FliG与跨膜蛋白FliF的结合是细菌鞭毛组装过程中最早的相互作用之一。一旦建立，这种相互作用对于保持鞭毛细胞质环是不可或缺的，它负责传递扭矩和控制鞭毛的旋转方向，锚定在鞭毛组装的中央跨膜环上。在这里，我们分离并表征了thermotoga maritimaFliG （FliGN）的n端结构域与ofT保守的c端部分对应的肽之间的相互作用。maritimaFliF。利用核磁共振（NMR）和其他技术，我们发现FliF的最后~ 40个氨基酸（FliFC）与FliGN强烈相互作用（在低纳摩尔范围内的上界）。这种复合物的形成引起FliGN中广泛的构象变化。我们找到了t。在缺少fllifc肽的情况下，maritimafligni是同二聚体，但与肽形成异二聚体复合物，并且我们表明在全长t中发生相同的低聚体状态变化。还有海事飞行。我们将先前观察到的flifc突变的表型效应与我们直接观察到的结合联系起来。最后，根据核磁共振数据，我们提出FliFCis的主要相互作用位点位于沿FliGN螺旋1为中心的保守疏水斑块上。这些结果为细菌鞭毛运动提供了新的详细信息，并支持理解细胞质环的精确分子结构和旋转开关机制。
The binding of the soluble cytoplasmic protein FliG to the transmembrane protein FliF is one of the first interactions in the assembly of the bacterial flagellum. Once established, this interaction is integral in keeping the flagellar cytoplasmic ring, responsible for both transmission of torque and control of the rotational direction of the flagellum, anchored to the central transmembrane ring on which the flagellum is assembled. Here we isolate and characterize the interaction between the N-terminal domain ofThermotoga maritimaFliG (FliGN) and peptides corresponding to the conserved C-terminal portion ofT. maritimaFliF. Using nuclear magnetic resonance (NMR) and other techniques, we show that the last ∼40 amino acids of FliF (FliFC) interact strongly (upper boundKdin the low nanomolar range) with FliGN. The formation of this complex causes extensive conformational changes in FliGN. We find thatT. maritimaFliGNis homodimeric in the absence of the FliFCpeptide but forms a heterodimeric complex with the peptide, and we show that this same change in oligomeric state occurs in full-lengthT. maritimaFliG, as well. We relate previously observed phenotypic effects of FliFCmutations to our direct observation of binding. Lastly, on the basis of NMR data, we propose that the primary interaction site for FliFCis located on a conserved hydrophobic patch centered along helix 1 of FliGN. These results provide new detailed information about the bacterial flagellar motor and support efforts to understand the cytoplasmic ring’s precise molecular structure and mechanism of rotational switching.