A SWITCH BETWEEN 2-STRANDED, 3-STRANDED AND 4-STRANDED COILED COILS IN GCN4 LEUCINE-ZIPPER MUTANTS
A SWITCH BETWEEN 2-STRANDED, 3-STRANDED AND 4-STRANDED COILED COILS IN GCN4 LEUCINE-ZIPPER MUTANTS
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DOI：
10.1126/science.8248779
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发表时间：
1993-11-26
期刊：
影响因子：
56.9
通讯作者：
ALBER, T
中科院分区：
文献类型：
--
作者：
HARBURY, PB;ZHANG, T;ALBER, T
蛋白质中的卷曲螺旋序列由含有两个特征性疏水位置的七肽重复序列组成。通过研究GCN 4亮氨酸拉链的突变体，研究了这些隐藏的疏水残基在确定卷曲螺旋结构中的作用。当被掩埋的残基组被改变时，形成了两个、三个和四个螺旋结构。四聚体的X射线晶体结构显示出平行的四股卷曲螺旋。 在四聚体构象中，七肽重复中的两个疏水位置的局部堆积几何形状相对于二聚体中的局部堆积几何形状是反转的。这些研究表明，保守的，隐藏在GCN 4亮氨酸拉链的残基直接二聚体的形成。 与蛋白质序列中疏水性和极性氨基酸的模式足以确定三维结构的建议相反，卷曲螺旋中隐藏的侧链的形状是全局折叠的重要决定因素。
Coiled-coil sequences in proteins consist of heptad repeats containing two characteristic hydrophobic positions. The role of these buried hydrophobic residues in determining the structures of coiled coils was investigated by studying mutants of the GCN4 leucine zipper. When sets of buried residues were altered, two-, three-, and four-helix structures were formed. The x-ray crystal structure of the tetramer revealed a parallel, four-stranded coiled coil. In the tetramer conformation, the local packing geometry of the two hydrophobic positions in the heptad repeat is reversed relative to that in the dimer. These studies demonstrate that conserved, buried residues in the GCN4 leucine zipper direct dimer formation. In contrast to proposals that the pattern of hydrophobic and polar amino acids in a protein sequence is sufficient to determine three-dimensional structure, the shapes of buried side chains in coiled coils are essential determinants of the global fold.