title: The bacterial flagellar protein export apparatus processively transports flagellar proteins even with extremely infrequent ATP hydrolysis.
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 α(3)β(3)γ complex of F(O)F(1)-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 FliI6FliJ ring is sufficient for gate activation, allowing processive translocation of export substrates for efficient flagellar assembly.
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Minamino
authors.affiliation: 1] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Riken Quantitative Biology Center, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan.
authors.forename: Yusuke V
authors.initials: YV
authors.lastname: Morimoto
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Centre for Bacterial Cell Biology, Medical Sciences New Building, Newcastle University, Richardson Road, Newcastle upon Tyne, United Kingdom, NE2 4AX.
authors.forename: Phillip D
authors.initials: PD
authors.lastname: Aldridge
authors.affiliation: 1] Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan [2] Riken Quantitative Biology Center, 6-2-3 Furuedai, Suita, Osaka 565-0874, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
mesh_terms: D000255:Adenosine Triphosphate / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D020125:Mutation, Missense; D021381:Protein Transport / Q000502:physiology; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D012475:Salmonella / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C069250:fliH protein, Bacteria; C069251:fliI protein, bacteria; C069253:fliJ protein, Bacteria; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases