title: Nanotransportation system for cholera toxin in Vibrio cholerae 01.
abstract: Vibrio cholerae (V. cholerae) cholera toxin (CT), which causes a severe watery diarrheal illness, is secreted via the type II secretion machinery; it remains unclear, however, how this toxin is transported toward the machinery. In this study, we determined that the pH-dependent intrabacterial transport system correlates with the priming of CT secretion by V. cholerae. The secretion and production of V. cholerae treated at different pHs were examined by enzyme immunoassay. The localization of the CT was analyzed by immunoelectron microscopy. The CT secretion level rapidly increases in the alkaline-pH-treated V. cholerae but does so more slowly in neutral- and acidic-pH-treated V. cholerae. The CT was found to be densely localized near the membrane in the alkaline-pH-treated bacterial cytoplasm, suggesting that the CT shifts from the center to the peripheral portion of the cytoplasm following an extracellular rise in pH. The shift was observed in V. cholerae treated at alkaline pH for more than 10 min. The pH treatment did not enhance CT production at the same stage at which secretion and intrabacterial transport of the CT were enhanced. We propose that V. cholerae possesses a pH-dependent intrabacterial nanotransportation system that probably accelerates priming for CT secretion.
authors.affiliation: Department of Microbiology and Infection Control, Osaka Medical College, 2-7 Daigaku-machi, Takatsuki, Osaka, 569-8686, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Aoki
authors.forename: Hong
authors.initials: H
authors.lastname: Wu
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
authors.forename: Yukimasa
authors.initials: Y
authors.lastname: Ooi
authors.forename: Eriko
authors.initials: E
authors.lastname: Daikoku
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kohno
authors.forename: Tomoyo
authors.initials: T
authors.lastname: Matsushita
authors.forename: Kouichi
authors.initials: K
authors.lastname: Sano
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D053768:Metal Nanoparticles; D016253:Microscopy, Immunoelectron; D008954:Models, Biological; D011956:Receptors, Cell Surface / Q000378:metabolism; D041241:Vibrio cholerae O1 / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D011956:Receptors, Cell Surface; D002772:Cholera Toxin