Occupancy of nonannular lipid binding sites on KcsA greatly increases the stability of the tetrameric protein.
Occupancy of nonannular lipid binding sites on KcsA greatly increases the stability of the tetrameric protein.
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KcsA 上非环状脂质结合位点的占据大大增加了四聚体蛋白的稳定性。
DOI：
10.1021/bi1003712
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发表时间：
2010
期刊：
影响因子：
2.9
通讯作者：
J. González
中科院分区：
文献类型：
--
作者：
I. Triano;F. Barrera;M. Renart;M. L. Molina;G. Fernández;J. A. Poveda;A. Fernández;J. Encinar;A. Ferrer;D. Otzen;J. González
KcsA是一种来自原核生物的同源四聚体钾通道，含有非共价结合的脂质，出现在蛋白质的X射线晶体结构中。这种高亲和力脂质的结合位点被称为“非环状”位点，对应于亚基间蛋白结构域，并优先结合阴离子磷脂。在这里，我们使用了热变性试验和洗涤剂-磷脂混合胶束含有KcsA研究不同的磷脂对蛋白质的稳定性的影响。我们发现，阴离子磷脂大大稳定的四聚体蛋白对不可逆的，热诱导的展开和解离成亚基。这以磷脂浓度依赖性方式发生，并且酰基链长度在14至18个碳原子范围内的磷脂酸物质在保护蛋白质方面比类似的磷脂酰甘油更有效。KcsA-磷脂复合物的对接模型表明，增加的蛋白质稳定性源于结合位点的亚基间性质，因此，磷脂与这些位点的相互作用将四聚体蛋白内的相邻亚基保持在一起。我们还发现，更简单的两亲物，如烷基硫酸酯长于10个碳原子，也增加了蛋白质的稳定性，在相同的程度上作为阴离子磷脂，虽然在更高的浓度比后者。建模这些简单的两亲物与KcsA的相互作用，并将其与阴离子磷脂的相互作用进行比较，以描绘在nonannular网站的疏水口袋的功能。预测这种口袋包含来自亚基的M2跨膜区段和来自相邻亚基的孔螺旋的残基，并且似乎与蛋白质稳定性最相关。
KcsA, a homotetrameric potassium channel from prokaryotes, contains noncovalently bound lipids appearing in the X-ray crystallographic structure of the protein. The binding sites for such high-affinity lipids are referred to as "nonannular" sites, correspond to intersubunit protein domains, and bind preferentially anionic phospholipids. Here we used a thermal denaturation assay and detergent-phospholipid mixed micelles containing KcsA to study the effects of different phospholipids on protein stability. We found that anionic phospholipids stabilize greatly the tetrameric protein against irreversible, heat-induced unfolding and dissociation into subunits. This occurs in a phospholipid concentration-dependent manner, and phosphatidic acid species with acyl chain lengths ranging 14 to 18 carbon atoms are more efficient than similar phosphatidylglycerols in protecting the protein. A docking model of the KcsA-phospholipid complex suggests that the increased protein stability originates from the intersubunit nature of the binding sites and, thus, interaction of the phospholipid with such sites holds together adjacent subunits within the tetrameric protein. We also found that simpler amphiphiles, such as alkyl sulfates longer than 10 carbon atoms, also increase the protein stability to the same extent as anionic phospholipids, although at higher concentrations than the latter. Modeling the interaction of these simpler amphiphiles with KcsA and comparing it with that of anionic phospholipids serve to delineate the features of a hydrophobic pocket in the nonannular sites. Such pocket is predicted to comprise residues from the M2 transmembrane segment of a subunit and from the pore helix of the adjacent subunit and seems most relevant to protein stabilization.
影响因子：
2.9
作者：
Valiyaveetil, FI;Zhou, YF;Mackinnon, R
通讯作者：
Mackinnon, R
心磷脂耗尽的牛心细胞色素 c 氧化酶：结合化学计量和对心磷脂衍生物的亲和力。
影响因子：
2.9
作者：
Robinson,NC;Zborowski,J;Talbert,LH
通讯作者：
Talbert,LH