title: Fuel of the Bacterial Flagellar Type III Protein Export Apparatus.
abstract: The flagellar type III export apparatus utilizes ATP and proton motive force (PMF) across the cytoplasmic membrane as the energy sources and transports flagellar component proteins from the cytoplasm to the distal growing end of the growing structure to construct the bacterial flagellum beyond the cellular membranes. The flagellar type III export apparatus coordinates flagellar protein export with assembly by ordered export of substrates to parallel with their order of the assembly. The export apparatus is composed of a PMF-driven transmembrane export gate complex and a cytoplasmic ATPase complex. Since the ATPase complex is dispensable for flagellar protein export, PMF is the primary fuel for protein unfolding and translocation. Interestingly, the export gate complex can also use sodium motive force across the cytoplasmic membrane in addition to PMF when the ATPase complex does not work properly. Here, we describe experimental protocols, which have allowed us to identify the export substrate class and the primary fuel of the flagellar type III protein export apparatus in Salmonella enterica serovar Typhimurium.
authors.affiliation: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan. tohru@fbs.osaka-u.ac.jp.
authors.forename: Tohru
authors.initials: T
authors.lastname: Minamino
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: Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.|Quantitative Biology Center, RIKEN, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Namba
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005407:Flagella / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology*; D018892:Proton-Motive Force / Q000502:physiology; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012486:Salmonella typhimurium / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006180:Proton-Translocating ATPases
keywords: ATPase; Flagellar assembly; Proton motive force; Sodium motive force; Substrate specificity switching; Type III protein export