Optical single-channel analysis of the aerolysin pore in erythrocyte membranes.
Scanning microphotolysis (Scamp), a recently developed photobleaching technique, was used to analyze the transport of two small organic anions and one inorganic cation through single pores formed in human erythrocyte membranes by the channel-forming toxin aerolysin secreted by Aeromonas species. The transport rate constants of erythrocyte ghosts carrying a single aerolysin pore were determined to be (1.83 +/- 0.43) x 10(-3) s-1 for Lucifer yellow, (0.33 +/- 0.10) x 10(-3) s-1 for carboxyfluorescein, and (8.20 +/- 2.30) x 10(-3) s-1 for Ca2+. The radius of the aerolysin pore was derived from the rate constants to be 19-23 A, taking steric hindrance and viscous drag into account. The size of the Ca2+ rate constant implies that at physiological extracellular Ca2+ concentrations (> 1 mM) the intracellular Ca2+ concentration would be elevated to the critical level of > 1 microM in much less than a second after formation of a single aerolysin pore in the plasma membrane. Thus changes in the levels of Ca2+ or other critical intracellular components may be more likely to cause cell death than osmotic imbalance.
Tschödrich-Rotter
M
M
Institut für Medizinische Physik und Biophysik, Westfälische Wilhelms-Universität, Münster, Germany.
Kubitscheck
U
U
Ugochukwu
G
G
Buckley
J T
JT
Peters
R
R
D000333:Aeromonas; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D055592:Biophysical Phenomena; D001703:Biophysics; D002118:Calcium / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002463:Cell Membrane Permeability; D004910:Erythrocyte Membrane / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006801:Humans; D066298:In Vitro Techniques; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D017136:Ion Transport / Q000502:physiology; D007546:Isoquinolines; D007700:Kinetics; D008954:Models, Biological; D015394:Molecular Structure; D010782:Photolysis; D052899:Pore Forming Cytotoxic Proteins
D001427:Bacterial Toxins; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007473:Ion Channels; D007546:Isoquinolines; D052899:Pore Forming Cytotoxic Proteins; C024098:6-carboxyfluorescein; C032676:aerolysin; C017475:lucifer yellow; D002118:Calcium