Pore-forming protein from Entamoeba histolytica forms voltage- and pH-controlled multi-state channels with properties similar to those of the barrel-stave aggregates.
Pore-forming protein from Entamoeba histolytica forms cation-selective channels in planar bilayers. With increasing potentials, the open-state probability of these channels decreases, and channel aggregates collapse (Young, J.D.-E. and Cohn, Z.A. (1985) J. Cell. Biochem. 29, 299-308). In this communication we report the following observations: (i) incorporation of the pore in black-lipid membranes was stimulated by membrane potential, (ii) pores were rectifying, (iii) breakdown of pores resulted in a continuous spectrum of subconductance states, (iv) the open-state probability increased strongly with pH. This pattern of behaviour is similar to that of the barrel-stave aggregates (alamethicin and related toxins). We therefore conclude that the amebal pores, like those of the barrel-stave class, may consist of complexes involving variable numbers of membrane-spanning subunits.
Keller
F
F
Universität Osnabrück, Department of Microbiology, F.R.G.
Hanke
W
W
Trissl
D
D
Bakker-Grunwald
T
T
D000818:Animals; D004553:Electric Conductivity; D004748:Entamoeba histolytica; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology* / Q000648:ultrastructure; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000502:physiology*; D015800:Protozoan Proteins
D007473:Ion Channels; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008565:Membrane Proteins; D015800:Protozoan Proteins; C041670:amoebapore proteins, protozoan