Calcium-modulated S100 protein-phospholipid interactions.: An NMR study of calbindin D9k and DPC
Calcium-modulated S100 protein-phospholipid interactions.: An NMR study of calbindin D9k and DPC
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DOI：
10.1021/bi050088z
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发表时间：
2005-05-03
期刊：
影响因子：
2.9
通讯作者：
Chazin, WJ
中科院分区：
文献类型：
--
作者：
Malmendal, A;Kooi, CWV;Chazin, WJ
几种S100蛋白的细胞功能涉及与磷脂和细胞膜的特异性相互作用。用核磁共振研究了钙结合蛋白D-9 k（S100 D）与洗涤剂十二烷基磷酸胆碱（DPC）的相互作用。在没有Call的情况下，蛋白质与DPC胶束缔合。胶束缔合状态具有完整的螺旋二级结构，但没有明显的三级折叠。在中性pH下，负载Ca 2+的钙结合蛋白D-9 k不与DPC胶束缔合。然而，在靠近两个EF-手之间的接头的位点处观察到与单个DPC分子的特异性相互作用。只有当Call与蛋白质结合时，才会与该位点结合。在不存在Ca 2+的情况下pH的降低增加了胶束缔合状态的稳定性。当pH降低时，这沿着相应的Call亲和力的降低也在Ca 2+的存在下引起向胶束缔合状态的转变。数据的位点特异性分析表明钙结合蛋白D-9 k具有三个紧密堆积的螺旋（A、B和D）的核心，其中动态第四螺旋（C）更松散地缔合。有证据表明，在胶束环境中的两个EF-手的钙离子结合特性是明显不同的。钙结合蛋白D9 k在细胞中的作用进行了讨论，沿着与S100蛋白家族的功能更广泛的影响。
The cellular functions of several S100 proteins involve specific interactions with phospholipids and the cell membrane. The interactions between calbindin D-9k (S100D) and the detergent dodecyl phosphocholine (DPC) were studied using NMR spectroscopy. In the absence of Call, the protein associates with DPC micelles. The micelle-associated state has intact helical secondary structures but no apparent tertiary fold. At neutral pH, Ca2+-loaded calbindin D-9k does not associate with DPC micelles. However, a specific interaction is observed with individual DPC molecules at a site close to the linker between the two EF-hands. Binding to this site occurs only when Call is bound to the protein. A reduction in pH in the absence of Ca2+ increases the stability of the micelle-associated state. This along with the corresponding reduction in Call affinity causes a transition to the micelle-associated state also in the presence of Ca2+ when the pH is lowered. Site-specific analysis of the data indicates that calbindin D-9k has a core of three tightly packed helices (A, B, and D), with a dynamic fourth helix (C) more loosely associated. Evidence is presented that the Ca2+-binding characteristics of the two EF-hands are distinctly different in a micelle environment. The role of calbindin D9k in the cell is discussed, along with the broader implications for the function of the S100 protein family.