1yrn
From Proteopedia
CRYSTAL STRUCTURE OF THE MATA1/MATALPHA2 HOMEODOMAIN HETERODIMER BOUND TO DNA
Structural highlights
Function[MTAL2_YEAST] Mating type proteins are sequence specific DNA-binding proteins that act as master switches in yeast differentiation by controlling gene expression in a cell type-specific fashion. Transcriptional corepressor that binds cooperatively with MCM1 to a 31-basepair DNA sequence termed the a-specific gene (asg) operator, to repress the transcription of a-cell-specific genes. Additionally, in a/alpha diploid cells, binds cooperatively with the A1 protein to a 21-basepair DNA sequence termed the haploid-specific gene (hsg) operator, to repress transcription of haploid-specific genes and of MATALPHA1.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe Saccharomyces cerevisiae MATa1 and MAT alpha 2 homeodomain proteins, which play a role in determining yeast cell type, form a heterodimer that binds DNA and represses transcription in a cell type-specific manner. Whereas the alpha 2 and a1 proteins on their own have only modest affinity for DNA, the a1/alpha 2 heterodimer binds DNA with high specificity and affinity. The three-dimensional crystal structure of the a1/alpha 2 homeodomain heterodimer bound to DNA was determined at a resolution of 2.5 A. The a1 and alpha 2 homeodomains bind in a head-to-tail orientation, with heterodimer contacts mediated by a 16-residue tail located carboxyl-terminal to the alpha 2 homeodomain. This tail becomes ordered in the presence of a1, part of it forming a short amphipathic helix that packs against the a1 homeodomain between helices 1 and 2. A pronounced 60 degree bend is induced in the DNA, which makes possible protein-protein and protein-DNA contacts that could not take place in a straight DNA fragment. Complex formation mediated by flexible protein-recognition peptides attached to stably folded DNA binding domains may prove to be a general feature of the architecture of other classes of eukaryotic transcriptional regulators. Crystal structure of the MATa1/MAT alpha 2 homeodomain heterodimer bound to DNA.,Li T, Stark MR, Johnson AD, Wolberger C Science. 1995 Oct 13;270(5234):262-9. PMID:7569974[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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