Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, 2109, Australia.
Eur Biophys J. 2009 Dec;39(1):129-38. doi: 10.1007/s00249-009-0450-0. Epub 2009 Apr 23.
Members of the chloride intracellular channel (CLIC) family exist primarily as soluble proteins but can also auto-insert into cellular membranes to form ion channels. While little is known about the process of CLIC membrane insertion, a unique feature of mammalian CLIC1 is its ability to undergo a dramatic structural metamorphosis between a monomeric glutathione-S-transferase homolog and an all-helical dimer upon oxidation in solution. Whether this oxidation-induced metamorphosis facilitates CLIC1 membrane insertion is unclear. In this work, we have sought to characterise the role of oxidation in the process of CLIC1 membrane insertion. We examined how redox conditions modify the ability of CLIC1 to associate with and insert into the membrane using fluorescence quenching studies and a sucrose-loaded vesicle sedimentation assay to measure membrane binding. Our results suggest that oxidation of monomeric CLIC1, in the presence of membranes, promotes insertion into the bilayer more effectively than the oxidised CLIC1 dimer.
氯离子通道（CLIC）家族的成员主要以可溶性蛋白的形式存在，但也可以自动插入细胞膜形成离子通道。虽然人们对 CLIC 膜插入的过程知之甚少，但哺乳动物 CLIC1 的一个独特特征是，它在溶液中氧化时能够在单体谷胱甘肽-S-转移酶同源物和全螺旋二聚体之间发生剧烈的结构变形。这种氧化诱导的变形是否有助于 CLIC1 插入细胞膜尚不清楚。在这项工作中，我们试图描述氧化在 CLIC1 膜插入过程中的作用。我们通过荧光猝灭研究和蔗糖负载囊泡沉淀测定来测量膜结合，研究了氧化还原条件如何改变 CLIC1 与膜结合和插入的能力。我们的结果表明，与氧化的 CLIC1 二聚体相比，存在膜时，单体 CLIC1 的氧化更有效地促进插入双层膜。
