Structural basis for the negative allostery between Ca2+- and Mg2+-binding in the intracellular Ca2+-receptor calbindin D-9k
Structural basis for the negative allostery between Ca2+- and Mg2+-binding in the intracellular Ca2+-receptor calbindin D-9k
复制标题
DOI：
10.1002/pro.5560060602
复制
发表时间：
1997-06-01
期刊：
影响因子：
8
通讯作者：
Svensson, LA
中科院分区：
文献类型：
--
作者：
Andersson, M;Malmendal, A;Svensson, LA
钙结合蛋白D-9 k的镁结合形式和锰结合形式的三维结构使用X射线晶体学分别确定为1.6埃和1.9埃分辨率。这两种结构几乎相同，但明显偏离钙结合形式和无金属离子（apo）形式。最大的结构差异出现在C-末端EF-手，并涉及金属离子配位和螺旋包装的变化。在镁和锰结构中，N-末端钙结合位点未被任何金属离子占据，并且与载脂蛋白和钙结合形式几乎没有结构偏差。在生理离子浓度下的H-1-NMR和UV光谱研究表明，蛋白质的C-末端位点在静息细胞钙水平下被镁显著填充，并且镁和钙结合之间存在负变构相互作用。钙结合被认为是发生在生理镁浓度的正协同性。
The three-dimensional structures of the magnesium- and manganese-bound forms of calbindin D-9k were determined to 1.6 Angstrom and 1.9 Angstrom resolution, respectively, using X-ray crystallography. These two structures are nearly identical but deviate significantly from both the calcium bound form and the metal ion-free (apo) form. The largest structural differences are seen in the C-terminal EF-hand, and involve changes in both metal ion coordination and helix packing. The N-terminal calcium binding site is not occupied by any metal ion in the magnesium and manganese structures, and shows little structural deviation from the apo and calcium bound forms. H-1-NMR and UV spectroscopic studies at physiological ion concentrations show that the C-terminal site of the protein is significantly populated by magnesium at resting cell calcium levels, and that there is a negative allosteric interaction between magnesium and calcium binding. Calcium binding was found to occur with positive cooperativity at physiological magnesium concentration.