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Microcin E492 forms ion channels in phospholipid bilayer membranes
Author(s) -
Lagos Rosalba,
Wilkens Marcela,
Vergara Cecilia,
Cecchi Ximena,
Monasterio Octavio
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80096-d
Subject(s) - phospholipid , ion channel , membrane , bilayer , chemistry , biophysics , lipid bilayer , ion transporter , biochemistry , biology , receptor
Microcin E492, a polypeptide antibiotic, has been shown to have an M r , of 6,000 by urea‐SDS‐polyacrylamide gel electrophoresis of the fluorescently labelled compound. It is known that the bactericidal action of microcin involves a loss of the transmembrane potential. In this study we show that microcin forms cation‐selective channels in planar phospholipid bilayers. The channels have two main conductance states the current‐voltage curves of which rectify. The reversal potentials measured under biionic conditions indicate a permeability sequence of NH 4 + > K + = Rb + = Cs + > Na + = Li + > Tris + . The results suggest that membrane potential dissipation induced by microcin is a consequence of the formation of pores in the bacterial membrane.