VOLTAGE-DEPENDENT CHANNELS FORMED BY COLICINS
KAGAN, BRUCE LAURENCE
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The bactericidal action of colicins K, E1, Ia and other functionally related colicins involves disruption of active transport and leakage of ions from the cell. I show that a single colicin molecule can form a voltage-dependent, relatively non-selective, ion permeable channel of a few picosiemens conductance in a planar phospholipid bilayer membrane. I suggest that the in vivo physiological effects of these colicins result from their ability to form ion-permeable channels in the bacterial inner membrane.;The voltage-dependent behavior of at least one colicin appears to be well described by a simple two state model based on the Boltzmann relation. The striking resemblance between the electrophysiology of the colicins and that of the voltage-dependent channels of nerve and muscle make the colicins an attractive model system for studying the molecular basis of ion channel gating.