Mutations in yeast HAP2/HAP3 define a hybrid CCAAT box binding domain

EMBO J. 1993 Dec;12(12):4647-55.


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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • CCAAT-Binding Factor*
  • DNA, Fungal / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Genes, Fungal
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Saccharomyces cerevisiae / genetics*
  • Schizosaccharomyces / genetics
  • Sequence Homology, Amino Acid
  • Suppression, Genetic
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • CCAAT-Binding Factor
  • DNA, Fungal
  • Fungal Proteins
  • Transcription Factors

Associated data

  • GENBANK/X75072