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The bacterial flagellar protein export apparatus processively transports flagellar proteins even with extremely infrequent ATP hydrolysis

Lookup NU author(s): Dr Phillip Aldridge

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Abstract

For self-assembly of the bacterial flagellum, a specific protein export apparatus utilizes ATP and proton motive force (PMF) as the energy source to transport component proteins to the distal growing end. The export apparatus consists of a transmembrane PMF-driven export gate and a cytoplasmic ATPase complex composed of FliH, FliI and FliJ. The FliI(6)FliJ complex is structurally similar to the alpha(3)beta(3)gamma complex of FOF1-ATPase. FliJ allows the gate to efficiently utilize PMF to drive flagellar protein export but it remains unknown how. Here, we report the role of ATP hydrolysis by the FliI(6)FliJ complex. The export apparatus processively transported flagellar proteins to grow flagella even with extremely infrequent or no ATP hydrolysis by FliI mutation (E211D and E211Q, respectively). This indicates that the rate of ATP hydrolysis is not at all coupled with the export rate. Deletion of FliI residues 401 to 410 resulted in no flagellar formation although this FliI deletion mutant retained 40% of the ATPase activity, suggesting uncoupling between ATP hydrolysis and activation of the gate. We propose that infrequent ATP hydrolysis by the FliI(6)FliJ ring is sufficient for gate activation, allowing processive translocation of export substrates for efficient flagellar assembly.


Publication metadata

Author(s): Minamino T, Morimoto YV, Kinoshita M, Aldridge PD, Namba K

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2014

Volume: 4

Online publication date: 22/12/2014

Acceptance date: 03/12/2014

Date deposited: 28/09/2015

ISSN (electronic): 2045-2322

Publisher: Nature Publishing Group

URL: http://dx.doi.org/10.1038/srep07579

DOI: 10.1038/srep07579


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