15N NMR relaxation studies of calcium-loaded parvalbumin show tight dynamics compared to those of other EF-hand proteins
15N NMR relaxation studies of calcium-loaded parvalbumin show tight dynamics compared to those of other EF-hand proteins
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DOI：
10.1021/bi980334p
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发表时间：
1998-07-14
期刊：
影响因子：
2.9
通讯作者：
Padilla, A
中科院分区：
文献类型：
--
作者：
Baldellon, C;Alattia, JR;Padilla, A
利用质子检测的异核磁共振波谱法测量N-15核弛豫，确定了大鼠cl-小白蛋白钙负载形式的动力学。利用谱密度函数和Lipari-Szabo形式分析弛化数据。大鼠α -小白蛋白钙负载形式的主要动力学特征是：(1)螺旋-环-螺旋EF-hand基序和连接它们的连接体片段的极端刚性，(2)蛋白质的N和C端在其迁移性上受到限制，(3)在螺旋D的连接处发生构象交换，(4)Ca2+结合位点相对位置2的残基具有增强的迁移性。比较α -小白蛋白-Ca2+，钙结合蛋白-Ca2+和钙调蛋白-Ca2+的Ca2+结合EF-hand结构域表明，小白蛋白可能是EF-hand蛋白中最刚性的。它还说明了这个超家族的不同成员在EF-hand结构域中保守的动力学性质：(1)在Ca2+结合环中相对位置2的NH向量具有较高的迁移率趋势，(2)结合环中其他残基的迁移率有限，以及(3)EF-hand基体螺旋的整体刚性。细小蛋白和两个EF手蛋白之间的移动性差异主要发生在连接一对EF手的连接器上，也发生在最后一个螺旋的C端。在细小蛋白ca2 +中，这两个区域的特点是与钙结合蛋白ca2 +和钙调素ca2 +中相应的更灵活的区域相比，具有明显的刚性。
Dynamics of the rat cl-parvalbumin calcium-loaded form have been determined by measurement of N-15 nuclear relaxation using proton-detected heteronuclear NMR spectroscopy. The relaxation data were analyzed using spectral density functions and the Lipari-Szabo formalism. The major dynamic features for the rat alpha-parvalbumin calcium-loaded form are (1) the extreme rigidity of the helix-loop-helix EF-hand motifs and the linker segment connecting them, (2) the N and C termini of the protein being restricted in their mobility, (3) a conformational exchange occurring at the kink of helix D, and (4) the residue at relative position 2 in the Ca2+-binding sites having an enhanced mobility. Comparison of the Ca2+-binding EF-hand domains of alpha-parvalbumin-Ca2+, calbindin-Ca2+, and calmodulin-Ca2+ shows that parvalbumin is probably the most rigid of the EF-hand proteins. It also illustrates the dynamical properties which are conserved in the EF-hand domains from different members of this superfamily: (1) a tendency toward higher mobility of NH vectors at relative position 2 in the Ca2+-binding loop, (2) a restricted mobility for the other residues in the binding loop, and (3) an overall rigidity for the helices of EF-hand motifs. The differences in mobility between parvalbumin and the two EF-hand proteins occur mainly at the linker connecting the pair of EF hands and also at the C terminus of the last helix. In parvalbumin-Ca2+, these two regions are characterized by a pronounced rigidity compared to the corresponding more mobile regions in calbindin-Ca2+ and calmodulin-Ca2+.