title: Studies on the energetics of proaerolysin secretion across the outer membrane of Aeromonas species. Evidence for a requirement for both the protonmotive force and ATP.
abstract: Aeromonas spp. secrete the channel-forming protein proaerolysin across their inner and outer membranes in separate steps using the general secretion pathway. Here we show that treating A. hydrophila or A. salmonicida with the protonophore carbonyl cyanide m-chorophenyl hydrazone blocks the second step in transport, secretion across the outer membrane from the periplasm, under conditions where the ATP levels in the cell are no different than the levels in control, secreting cells. A threshold for DeltaPsi was observed in the region of 120 mV, below which secretion by both species was inhibited. Treatment of cells with arsenate, which lowered ATP levels but did not affect DeltaPsi, also reduced secretion from the periplasm, an indication that there is an ATP requirement for this step independent of the requirement for DeltaPsi. Secretion across the outer membrane was also arrested by increasing the osmotic pressure of the medium, even though cellular ATP levels and DeltaPsi were not affected. This may be due to disruption of some necessary association between the inner and outer membranes.
authors.affiliation: Laboratoire des Biomembranes, URA CNRS 1116, Université Paris-Sud, Bâtiment 432, F-91405 Orsay, France.
authors.forename: L
authors.initials: L
authors.lastname: Letellier
authors.forename: S P
authors.initials: SP
authors.lastname: Howard
authors.forename: J T
authors.initials: JT
authors.lastname: Buckley
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000333:Aeromonas / Q000378:metabolism*; D001149:Arsenates / Q000494:pharmacology; D001427:Bacterial Toxins / Q000378:metabolism*; D001693:Biological Transport, Active; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006460:Hemolysin Proteins / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007473:Ion Channels / Q000378:metabolism*; D007476:Ionophores / Q000494:pharmacology; D009997:Osmotic Pressure; D052899:Pore Forming Cytotoxic Proteins; D011498:Protein Precursors / Q000378:metabolism*; D018892:Proton-Motive Force
chemical_list: D001149:Arsenates; D001427:Bacterial Toxins; D004791:Enzyme Inhibitors; D006460:Hemolysin Proteins; D007473:Ion Channels; D007476:Ionophores; D052899:Pore Forming Cytotoxic Proteins; D011498:Protein Precursors; C032676:aerolysin; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate; C025657:arsenic acid