Lipid-mediated inactivation of colicin E1 channels by calcium ions.
Based on the model of a toroidal protein-lipid pore, the effect of calcium ions on colicin E1 channel was predicted. In electrophysiological experiments Ca2+ suppressed the activity of colicin E1 channels in membranes formed of diphytanoylphosphatidylglycerol, whereas no desorption of the protein occurred from the membrane surface. The effect of Ca2+ was not observed on membranes formed of diphytanoylphosphatidylcholine. Single-channel measurements revealed that Ca2+-induced reduction of the colicin-induced current across the negatively charged membrane was due to a decrease in the number of open colicin channels and not changes in their properties. In line with the toroidal model, the effect of Ca2+ on the colicin E1 channel-forming activity is explained by alteration of the membrane lipid curvature caused by electrostatic interaction of Ca2+ with negatively charged lipid head groups.
Sobko
A A
AA
Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
Kotova
E A
EA
Zakharov
S D
SD
Cramer
W A
WA
Antonenko
Y N
YN
D002118:Calcium / Q000378:metabolism*; D003087:Colicins / Q000378:metabolism*; D004553:Electric Conductivity; D007473:Ion Channels / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry
D003087:Colicins; D007473:Ion Channels; D008051:Lipid Bilayers; D008055:Lipids; D002118:Calcium