title: Structure of HAP1-18-DNA implicates direct allosteric effect of protein-DNA interactions on transcriptional activation.
abstract: HAP1 is a yeast transcriptional activator that binds with equal affinity to the dissimilar upstream activation sequences UAS1 and UAS(CYC7), but activates transcription differentially when bound to each site. HAP1-18 harbors an amino acid change in the DNA binding domain. While binding UAS1 poorly, HAP1-18 binds UAS(CYC7) with wild-type properties and activates transcription at elevated levels relative to HAP1. We have determined the structure of HAP1-18-UAS(CYC7) and have compared it to HAP1-UAS(CYC7). Unexpectedly, the single amino acid substitution in HAP1-18 nucleates a significantly altered hydrogen bond interface between the protein and DNA resulting in DNA conformational changes and an ordering of one N-terminal arm of the protein dimer along the DNA minor groove. These observations, together with a large subset of transcriptionally defective mutations in the HAP1 DNA-binding domain that map to the HAP1-DNA interface, suggest that protein-DNA interactions may have direct allosteric effects on transcriptional activation.
authors.affiliation: The Wistar Institute and The Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: King
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Guarente
authors.forename: R
authors.initials: R
authors.lastname: Marmorstein
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D019757:Carbon-Oxygen Lyases / Q000737:chemistry* / Q000378:metabolism; D004271:DNA, Fungal / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012441:Saccharomyces cerevisiae; D015533:Transcriptional Activation
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D019757:Carbon-Oxygen Lyases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase