期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：16
页码：6901-6905
DOI：10.1073/pnas.88.16.6901
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The bZIP structural motif present in several eukaryotic transcription factors is defined by the leucine zipper, a coiled-coil dimerization interface, and an adjacent basic region that directly interacts with DNA. To examine the functional importance of the highly conserved spacing between the leucine zipper and the basic region, we have analyzed the DNA-binding ability of yeast GCN4 proteins containing amino acid insertions between these two subdomains. Proteins containing a surprisingly wide variety of seven-amino acid insertions, but none containing two-, four-, or six-amino acid insertions, are functional. However, heterodimers between wild-type GCN4 and functional derivatives containing seven amino acid insertions are unable to bind DNA. These observations provide strong experimental support for several aspects of the scissors grip and induced fork models for DNA-binding by bZIP proteins. Specifically, they demonstrate that continuous alpha-helices symmetrically diverging from the leucine zipper correctly position the two basic regions for specific binding to abutting DNA half-sites. In addition, the results indicate that GCN4 homodimers are primarily responsible for transcriptional activation in yeast cells.
