期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1979
卷号：76
期号：12
页码：6167-6171
DOI：10.1073/pnas.76.12.6167
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Colicins Ia and E1 are shown to inhibit the formation and bring about the collapse of a potassium diffusion potential imposed across the membrane of liposomes prepared from soybean or Escherichia coli phospholipids. Such depolarization results from a colicin-induced increase in membrane ion permeability. Colicins E2 and E3 do not depolarize such membranes. In addition to the colicin Ia-induced rapid efflux of preloaded rubidium, sodium, phosphate, or choline from liposomes, a slower efflux of preloaded sucrose or glucose 6-phosphate occurs. However, treated liposomes do not leak inulin or dextran, demonstrating that the effects of E1 and Ia are not due to a general disruption of membrane structure. The fact that colicin-induced ion efflux is observed in the complete absence of a membrane potential shows that the action of these colicins on liposomes is not voltage dependent. These results provide strong evidence that the depolarization of E. coli cells by colicins Ia and E1 results from a colicin-induced increase in membrane permeability to ions. It is proposed that this is brought about by the direct interaction of the colicin molecules with the bacterial cytoplasmic membrane.
