Subconductance states in OmpF gating
Subconductance states in OmpF gating
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DOI：
10.1016/j.bbamem.2004.04.009
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发表时间：
2004-07-01
影响因子：
3.4
通讯作者：
Delcour, AH
中科院分区：
文献类型：
--
作者：
Baslé, A;Iyer, R;Delcour, AH
在已发表的大肠杆菌孔蛋白OmpF的电导中注意到了差异。由于使用了不同的通道制剂、盐类型和浓度以及电生理技术（黑脂质膜（BLM）与膜片钳），因此很难比较不同论文的结果。为了调和这些数据，我们提出了一个并排比较OmpF活性研究与两种技术在同一制备的纯蛋白质，并在相同的低盐浓度（150 mM KCl）。通过这种比较揭示的OmpF孔蛋白行为的新方面是普遍存在的状态比单体电导（亚电导状态）的电导更小，无论使用的技术或实验条件，和多胺的亚电导门控的急剧增强。在以前的出版物中，特别是当使用BLM电生理学时，很少注意到亚电导状态的转变。在钳位电位下，单体闭合很少出现，至少在低于100 -120 mV的电压下。大多数闭合活动以亚电导门控的形式出现，在精胺存在下，亚电导门控变得更占主导地位，占据这些亚状态的时间更长，更频繁。孔蛋白的这种标志性行为的分子基础的讨论。(C)2004 Elsevier B. V.保留所有权利。
Discrepancies were noted in the published conductance of the Escherichia coli porin OmpF. Results from various papers are hard to compare because of the use of different channel preparations, salt types and concentrations, and electrophysiological techniques (black lipid membrane (BLM) vs. patch clamp). To reconcile these data, we present a side-by-side comparison of OmpF activity studied with the two techniques on the same preparation of pure protein, and in the same low salt concentrations (150 mM KCl). The novel aspect of OmpF porin behavior revealed by this comparison is the ubiquitous existence of states of smaller conductance than the monomeric conductance (subconductance states), regardless of the techniques or experimental conditions used, and the drastic enhancement of subconductance gating by polyamines. Transitions to subconductance states have received little attention in previous publications, in particular when BLM electrophysiology was used. Monomeric closures are rare in recordings at clamped potentials, at least at voltages lower than similar to100-120 mV Most closing activity is in the form of subconductance gating, which becomes more dominant in the presence of spermine, with a more frequent and prolonged occupation of these substates. A discussion of the molecular basis for this hallmark behavior of porin is presented. (C) 2004 Elsevier B.V. All rights reserved.