title: Structure of the C-terminal domain of Tup1, a corepressor of transcription in yeast.
abstract: The Tup1-Ssn6 corepressor complex regulates the expression of several sets of genes, including genes that specify mating type in the yeast Saccharomyces cerevisiae. Repression of mating-type genes occurs when Tup1-Ssn6 is brought to the DNA by the Matalpha2 DNA-binding protein and assembled upstream of a- and haploid-specific genes. We have determined the 2.3 A X-ray crystal structure of the C-terminal domain of Tup1 (accesion No. 1ERJ), a 43 kDa fragment that contains seven copies of the WD40 sequence motif and binds to the Matalpha2 protein. Moreover, this portion of the protein can partially substitute for full-length Tup1 in bringing about transcriptional repression. The structure reveals a seven-bladed beta propeller with an N-terminal subdomain that is anchored to the side of the propeller and extends the beta sheet of one of the blades. Point mutations in Tup1 that specifically affect the Tup1-Matalpha2 interaction cluster on one surface of the propeller. We identified regions of Tup1 that are conserved among the fungal Tup1 homologs and may be important in protein-protein interactions with additional components of the Tup1-mediated repression pathways.
authors.affiliation: Department of Biophysics and Biophysical Chemistry and Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Sprague
authors.forename: M J
authors.initials: MJ
authors.lastname: Redd
authors.forename: A D
authors.initials: AD
authors.lastname: Johnson
authors.forename: C
authors.initials: C
authors.lastname: Wolberger
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010446:Peptide Fragments / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D020449:Repetitive Sequences, Amino Acid; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D018398:Homeodomain Proteins; C062928:MATA2 protein, S cerevisiae; D009687:Nuclear Proteins; D010446:Peptide Fragments; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C066502:TUP1 protein, S cerevisiae