Lagos R, Wilkens M, Vergara C, Cecchi X, Monasterio O
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
FEBS Lett. 1993 Apr 26;321(2-3):145-8. doi: 10.1016/0014-5793(93)80096-d.
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.
微菌素E492是一种多肽抗生素，通过对荧光标记化合物进行尿素 - SDS - 聚丙烯酰胺凝胶电泳显示其分子量为6000。已知微菌素的杀菌作用涉及跨膜电位的丧失。在本研究中，我们表明微菌素在平面磷脂双分子层中形成阳离子选择性通道。这些通道有两个主要的电导状态，其电流 - 电压曲线呈整流性。在双离子条件下测得的反转电位表明通透性顺序为NH4+ > K+ = Rb+ = Cs+ > Na+ = Na+ = Li+ > Tris+。结果表明，微菌素诱导的膜电位消散是细菌膜中形成孔道的结果。
