Buechner M, Delcour A H, Martinac B, Adler J, Kung C
Department of Biochemistry and Genetics, University of Wisconsin, Madison 53706.
Biochim Biophys Acta. 1990 May 9;1024(1):111-21. doi: 10.1016/0005-2736(90)90214-9.
The electrical properties of Escherichia coli cells were examined by the patch-clamp technique. Giant cells or giant spheroplasts were generated by five different methods. By electron micrographic and other criteria we determined that the patches are most likely from the outer membrane. We regularly observed currents through at least two types of channels in this membrane. The first current is mechanosensitive and voltage-dependent, and can be observed in single gene mutants of the known major porins (ompF, ompC, phoE, lamB); this channel may represent a minor porin or a new class of outer membrane protein. The possible identity of the second, voltage-sensitive channel with one of the known outer membrane proteins is being explored. The high-resistance seals consistently formed on these patches and the presence of gated ion channels suggest that most of the pores of the outer membrane are not statically open, as commonly held, but are closed at rest and may be openable by physiological stimuli.
通过膜片钳技术检测了大肠杆菌细胞的电特性。采用五种不同方法制备了巨大细胞或巨大原生质球。通过电子显微镜及其他标准，我们确定这些膜片极有可能来自外膜。我们经常观察到该膜中至少存在两种类型通道的电流。第一种电流是机械敏感且电压依赖性的，在已知主要孔蛋白（ompF、ompC、phoE、lamB）的单基因突变体中也可观察到；该通道可能代表一种次要孔蛋白或一类新型外膜蛋白。正在探索第二种电压敏感通道与已知外膜蛋白之一的可能一致性。在这些膜片上持续形成的高电阻封接以及门控离子通道的存在表明，外膜的大多数孔并非如通常所认为的那样静态开放，而是在静息时关闭，并且可能可被生理刺激打开。
