title: The channel-forming protein proaerolysin remains a dimer at low concentrations in solution.
abstract: Proaerolysin, the proform of the channel-forming protein aerolysin, is secreted as a dimer by Aeromonas sp. The protein also exists as a dimer in the crystal, as well as in solution, at least at concentrations in the region of 500 microg/ml. Recently it has been argued that proaerolysin becomes monomeric at concentrations below 100 microg/ml and that only the monomeric form of the protoxin can bind to cell surface receptors (Fivaz, M., Velluz, M.-C., and van der Goot, F. G. (1999) J. Biol. Chem. 274, 37705-37708). Here we show, using non-denaturing polyacrylamide electrophoresis, chemical cross-linking, and analytical ultracentrifugation, that proaerolysin remains dimeric at the lowest concentrations of the protein that we measured (less than 5 microg/ml) and that the dimeric protoxin is quite capable of receptor binding.
authors.affiliation: Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Barry
authors.forename: S
authors.initials: S
authors.lastname: Moore
authors.forename: A
authors.initials: A
authors.lastname: Alonso
authors.forename: J
authors.initials: J
authors.lastname: Ausió
authors.forename: J T
authors.initials: JT
authors.lastname: Buckley
mesh_terms: D000333:Aeromonas / Q000737:chemistry*; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000378:metabolism; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism; D006801:Humans; D007473:Ion Channels / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008970:Molecular Weight; D009154:Mutation; D052899:Pore Forming Cytotoxic Proteins; D011485:Protein Binding; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary; D013388:Succinimides / Q000378:metabolism; D014461:Ultracentrifugation
chemical_list: D001427:Bacterial Toxins; D003432:Cross-Linking Reagents; D007473:Ion Channels; D052899:Pore Forming Cytotoxic Proteins; D011498:Protein Precursors; D013388:Succinimides; C107096:proaerolysin; C032676:aerolysin; C011240:dithiobis(succinimidylpropionate)