title: Colicin K acts by forming voltage-dependent channels in phospholipid bilayer membranes.
abstract: 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. We show that a single colicin K molecule can form a voltage-dependent, relatively nonselective, ion-permeable channel of a few picosiemens conductance in a planar phospholipid bilayer membrane. In a membrane containing many of these channels, the ratio of the number of conducting to nonconducting channels changes e-fold per 3.7 mV. We suggest that the physiological effects of colicin K and functionally related colicins result from their ability to form ion-permeable channels in the bacterial plasma membrane.
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D003087:Colicins / Q000494:pharmacology*; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects*; D008563:Membrane Lipids; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins; D008567:Membranes, Artificial; D008954:Models, Biological; D010743:Phospholipids; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D003087:Colicins; D007473:Ion Channels; D008563:Membrane Lipids; D008565:Membrane Proteins; D008567:Membranes, Artificial; D010743:Phospholipids; D014475:Uncoupling Agents