Ellenberger T E, Brandl C J, Struhl K, Harrison S C
Harvard University, Department of Biochemistry and Molecular Biology, Cambridge, Massachusetts 02138.
Cell. 1992 Dec 24;71(7):1223-37. doi: 10.1016/s0092-8674(05)80070-4.
The yeast transcriptional activator GCN4 is 1 of over 30 identified eukaryotic proteins containing the basic region leucine zipper (bZIP) DNA-binding motif. We have determined the crystal structure of the GCN4 bZIP element complexed with DNA at 2.9 A resolution. The bZIP dimer is a pair of continuous alpha helices that form a parallel coiled coil over their carboxy-terminal 30 residues and gradually diverge toward their amino termini to pass through the major groove of the DNA-binding site. The coiled-coil dimerization interface is oriented almost perpendicular to the DNA axis, giving the complex the appearance of the letter T. There are no kinks or sharp bends in either bZIP monomer. Numerous contacts to DNA bases and phosphate oxygens are made by basic region residues that are conserved in the bZIP protein family. The details of the bZIP dimer interaction with DNA can explain recognition of the AP-1 site by the GCN4 protein.
酵母转录激活因子GCN4是已鉴定出的30多种含有碱性区域亮氨酸拉链（bZIP）DNA结合基序的真核蛋白之一。我们已确定GCN4 bZIP元件与DNA复合物的晶体结构，分辨率为2.9埃。bZIP二聚体是一对连续的α螺旋，在其羧基末端30个残基上形成平行卷曲螺旋，并在其氨基末端逐渐分开，以穿过DNA结合位点的大沟。卷曲螺旋二聚化界面几乎垂直于DNA轴，使复合物呈现字母T的外观。bZIP单体中均没有扭结或急转弯。bZIP蛋白家族中保守的碱性区域残基与DNA碱基和磷酸氧形成了大量接触。bZIP二聚体与DNA相互作用的细节可以解释GCN4蛋白对AP-1位点的识别。
