Nature：细菌鞭毛分泌的动力来源并非ATP酶
生物谷报道：细菌鞭毛包含一个分泌器，它与很多病原体用来将效应器（effector）蛋白转移进宿主细胞内的III-型分泌体系相关。科学家认为，ATP酶FliL为这种输送提供能量，但本期Nature上两篇论文反对这一被普遍接受的观点。这两个研究小组都发现，鞭毛分泌即使是在没有这种ATP酶的情况下也能发生，而且为该过程提供能量的是质子运动力。
生物谷推荐英文原文：
Nature 451, 485-488 (24 January 2008) | doi:10.1038/nature06449; Received 8 August 2007; Accepted 29 October 2007
Distinct roles of the FliI ATPase and proton motive force in bacterial flagellar protein export
Tohru Minamino1,2 & Keiichi Namba1,2
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- Dynamic NanoMachine Project, ICORP, JST, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
Correspondence to: Keiichi Namba1,2 Correspondence and requests for materials should be addressed to K.N. (Email: keiichi@fbs.osaka-u.ac.jp).
Translocation of many soluble proteins across cell membranes occurs in an ATPase-driven manner. For construction of the bacterial flagellum responsible for motility, most of the components are exported by the flagellar protein export apparatus1, 2. The FliI ATPase is required for this export3, and its ATPase activity is regulated by FliH4; however, it is unclear how the chemical energy derived from ATP hydrolysis is used for the export process. Here we report that flagellar proteins of Salmonella enterica serovar Typhimurium are exported even in the absence of FliI. A fliH fliI double null mutant was weakly motile. Certain mutations in FlhA or FlhB, which form the core of the export gate, substantially improved protein export and motility of the double null mutant. Furthermore, proton motive force was essential for the export process. These results suggest that the FliH–FliI complex facilitates only the initial entry of export substrates into the gate, with the energy of ATP hydrolysis being used to disassemble and release the FliH–FliI complex from the protein about to be exported. The rest of the successive unfolding/translocation process of the substrates is driven by proton motive force.
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