Microcin E492 forms ion channels in phospholipid bilayer membrane - PubMed (original) (raw)

Microcin E492 forms ion channels in phospholipid bilayer membrane

R Lagos et al. FEBS Lett. 1993.

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Abstract

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 NH4+ > K+ = Rb+ = Cs+ > Na+ = 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.

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