The FliN-FliH interaction mediates localization of flagellar export ATPase FliI to the C ring complex
The FliN-FliH interaction mediates localization of flagellar export ATPase FliI to the C ring complex
复制标题
DOI：
10.1021/bi0605890
复制
发表时间：
2006-10-03
期刊：
影响因子：
2.9
通讯作者：
Gonzalez-Pedrajo, Bertha
中科院分区：
文献类型：
--
作者：
McMurry, Jonathan L.;Murphy, James W.;Gonzalez-Pedrajo, Bertha
FliH调节鞭毛输出ATPase FliI，防止非生产性的ATP水解。FliH已被证明与C环蛋白flin稳定结合。对该复合体的分析表明，FliH是FliI定位到C环所必需的，因此FliH不仅可以抑制FliI ATPase的活性，还可以将FliI靶向基底体。定量结合研究表明，FliH与flin结合的K-D为110 nM。温度敏感型非鞭毛FIN点突变体的FliH结合的Kd值为270 nM，这为其表型提供了分子解释。来自不同表型的温度敏感型突变体的另一个变异体flin显示与中等亲和力的结合。FliI的过量生产极大地增加了FliN缺失突变体的弱出口活性，模拟了先前观察到的FliH旁路效应，支持了Flin-FliH结合对于FliI与C环的定位以及因此膜包埋的出口装置的定位非常重要的结论。最后给出了一个包含本研究结果的模型。
FliH regulates the flagellar export ATPase FliI, preventing nonproductive ATP hydrolysis. FliH has been shown to stably associate with the C ring protein FliN. Analysis of this complex reveals that FliH is required for FliI localization to the C ring, and thus FliH not only inhibits FliI ATPase activity but also may act to target FliI to the basal body. Quantitative binding studies revealed a K-D of 110 nM for FliH binding to FliN. The KD for FliH binding of a FliN variant from a temperature-sensitive nonflagellate fliN point mutant was determined to be 270 nM, suggesting a molecular explanation for its phenotype. Another variant FliN from a temperature-sensitive mutant with a different phenotype displayed binding with an intermediate affinity. Weak export activity in a fliN null mutant was greatly increased by overproduction of FliI, mimicking a previously observed FliH bypass effect and supporting the conclusion that FliN-FliH binding is important for localization of FliI to the C ring and thus the membrane-embedded export apparatus beyond. A model incorporating the present findings is presented.