Three-dimensional solution structure of the calcium-signaling protein apo-S100A1 as determined by NMR.
Three-dimensional solution structure of the calcium-signaling protein apo-S100A1 as determined by NMR.
复制标题
通过 NMR 测定钙信号蛋白 apo-S100A1 的三维溶液结构。
DOI：
10.1021/bi0118308
复制
发表时间：
2002
期刊：
影响因子：
2.9
通讯作者：
Weber,DavidJ
中科院分区：
文献类型：
--
作者：
Rustandi,RichardR;Baldisseri,DonnaM;Inman,KeithG;Nizner,Peter;Hamilton,ShannonM;Landar,Aimee;Landar,Alexander;Zimmer,DannaB;Weber,DavidJ
S100A1是S100蛋白家族中的一员，是一种含钙结合蛋白(每个亚基93个残基)的EF-Hand蛋白，其二聚体界面存在非共价相互作用。S100A1的每个亚基都有四个α-螺旋和一个小的反平行β-折叠，与两个螺旋−环−螺旋钙结合结构域一致[Baldiserri等人。(1999)J.Biolol.NMR14，87−88]。在本研究中，通过核磁共振谱确定了还原的apo-S100A1的三维结构，总共使用了2220个NOE距离约束、258个二面角约束和168个主链氢键约束，这些约束来自一系列2D、3D和4D核磁共振实验。最终的结构是球状和致密的，每个亚基中的四个螺旋排列成一个独花型四螺旋束。从一个亚基到另一个亚基的螺旋1‘和4’的残基之间分别观察到分子间的NOE相关性，这与两个亚基的反平行排列形成对称的X型四螺旋束相一致，这与S100蛋白家族的其他成员一样。由于S100A1二聚体界面与S100B的界面相似，因此有可能计算S100A1/B异质二聚体的模型。这个模型与S100A1滴定到15N标记的S100B样品中时观察到的一些核磁共振化学位移变化是一致的。S100A1的螺旋3(和3‘)在−状态下与螺旋4(和4’)的螺旋夹角为150°。这个交叉角度(>；50°)与其他含有载脂蛋白和载脂蛋白C的EF-Hand蛋白中典型的不同，但更类似于APO-S100B，它的螺旋间角为−166°。与S100B一样，apo-S100A1的第二只EF-手很可能在钙离子的作用下发生显著的重新定位，这可以解释S100A1与其几个生物靶点结合对钙的依赖性。
S100A1, a member of the S100 protein family, is an EF-hand containing Ca2+-binding protein (93 residues per subunit) with noncovalent interactions at its dimer interface. Each subunit of S100A1 has four α-helices and a small antiparallel β-sheet consistent with two helix−loop−helix calcium-binding domains [Baldiserri et al. (1999)J. Biomol. NMR14,87−88]. In this study, the three-dimensional structure of reduced apo-S100A1 was determined by NMR spectroscopy using a total of 2220 NOE distance constraints, 258 dihedral angle constraints, and 168 backbone hydrogen bond constraints derived from a series of 2D, 3D, and 4D NMR experiments. The final structure was found to be globular and compact with the four helices in each subunit aligning to form a unicornate-type four-helix bundle. Intermolecular NOE correlations were observed between residues in helices 1 and 4 from one subunit to residues in helices 1‘ and 4‘ of the other subunit, respectively, consistent with the antiparallel alignment of the two subunits to form a symmetric X-type four-helix bundle as found for other members of the S100 protein family. Because of the similarity of the S100A1 dimer interface to that found for S100B, it was possible to calculate a model of the S100A1/B heterodimer. This model is consistent with a number of NMR chemical shift changes observed when S100A1 is titrated into a sample of15N-labeled S100B. Helix 3 (and 3‘) of S100A1 was found to have an interhelical angle of −150° with helix 4 (and 4‘) in the apo state. This crossing angle is quite different (>50°) from that typically found in other EF-hand containing proteins such as apocalmodulin and apotroponin C but more similar to apo-S100B, which has an interhelical angle of −166°. As with S100B, it is likely that the second EF-hand of apo-S100A1 reorients dramatically upon the addition of Ca2+, which can explain the Ca2+dependence that S100A1 has for binding several of its biological targets.