Mutations in yeast HAP2/HAP3 define a hybrid CCAAT box binding domain.
We describe a detailed genetic analysis of the DNA-binding regions in the HAP2/HAP3 CCAAT-binding heteromeric complex. The DNA-binding domain of HAP2 is shown to be a 21 residue region containing three critical histidines and three critical arginines. Mutation of an arginine at position 199 to leucine alters the DNA-binding specificity of the complex to favor CCAAC over CCAAT. Residues in HAP3 that are critical for DNA-binding comprise a short, seven amino acid region. Three different mutations in the HAP2 DNA-binding domain are suppressed by a mutation in the HAP3 DNA-binding domain. This HAP3 mutation also suppresses mutations in a different region of HAP2 which promotes subunit assembly of the complex. These findings suggest that short regions of HAP2 and HAP3 comprise a hybrid DNA-binding domain and that this domain can help hold the two subunits together in the CCAAT-binding complex.
Xing
Y
Y
Department of Biology, MIT, Cambridge, MA 02139.
Fikes
J D
JD
Guarente
L
L
D000595:Amino Acid Sequence; D001665:Binding Sites; D023081:CCAAT-Binding Factor; D004271:DNA, Fungal / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013489:Suppression, Genetic; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D023081:CCAAT-Binding Factor; D004271:DNA, Fungal; D005656:Fungal Proteins; D014157:Transcription Factors