CRYSTAL-STRUCTURE OF AN ISOLEUCINE-ZIPPER TRIMER
CRYSTAL-STRUCTURE OF AN ISOLEUCINE-ZIPPER TRIMER
复制标题
DOI：
10.1038/371080a0
复制
发表时间：
1994-09-01
期刊：
影响因子：
64.8
通讯作者：
ALBER, T
中科院分区：
文献类型：
--
作者：
HARBURY, PB;KIM, PS;ALBER, T
许多蛋白质中的亚单位寡聚化由短卷曲螺旋基序介导（1，2）。这些基序共享在第一（a）和第四（d）位置含有疏水残基的特征性七氨基酸重复。尽管有这种共同的模式，不同的序列形成两股、三股和四股螺旋绳。我们已经通过表征GCN 4亮氨酸拉链二聚化结构域的变体（3）研究了寡聚体选择的基础，所述变体（3）响应于a和d位置处的突变而采用三聚体或四聚体结构。我们现在报告的高分辨率X射线晶体结构的异亮氨酸含有突变体折叠成一个平行的三链，α-螺旋卷曲螺旋。与二聚体和四聚体结构（3，4）相反，三聚体的内部包装可以在两个疏水位置处容纳最优选的旋转异构体中的β-支链残基。核心氨基酸的形状与两链、三链和四链构象中的不同包装空间的相容性似乎决定了GCN 4亮氨酸拉链变体的寡聚化状态。
SUBUNIT oligomerization in many proteins is mediated by short coiled-coil motifs(1,2). These motifs share a characteristic seven-amino-acid repeat containing hydrophobic residues at the first (a) and fourth (d) positions. Despite this common pattern, different sequences form two-, three- and four-stranded helical ropes. We have investigated the basis for oligomer choice by characterizing variants(3) of the GCN4 lencine-zipper dimerization domain that adopt trimeric or tetrameric structures in response to mutations at the a and d positions. We now report the high-resolution X-ray crystal structure of an isoleucine-containing mutant that folds into a parallel three-stranded, alpha-helical coiled coil. In contrast to the dimer and tetramer structures(3,4), the interior packing of the trimer can accommodate beta-branched residues in the most preferred rotamer at both hydrophobic positions. Compatibility of the shape of the core amino acids with the distinct packing spaces in the two-, three- and four-stranded conformations appears to determine the oligomerization state of the GCN4 leucine-zipper variants.