A new use for the 'wing' of the 'winged' helix-turn-helix motif in the HSF-DNA cocrystal.
The 1.75 A crystal structure of the Kluyveromyces lactis heat shock transcription factor (HSF) DNA-binding domain (DBD) complexed with DNA reveals a protein-DNA interface with few direct major groove contacts and a number of phosphate backbone contacts that are primarily water-mediated interactions. The DBD, a 'winged' helix-turn-helix protein, displays a novel mode of binding in that the 'wing' does not contact DNA like all others of that class. Instead, the monomeric DBD, which crystallized as a symmetric dimer to a pair of nGAAn inverted repeats, uses the 'wing' to form part of the protein-protein contacts. This dimer interface is likely important for increasing the DNA-binding specificity and affinity of the trimeric form of HSF, as well as for increasing cooperativity between adjacent trimers.
Littlefield
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Department of Molecular and Cell Biology, University of California, Berkeley 94720-3206, USA.
Nelson
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HC
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D019077:Helix-Turn-Helix Motifs / Q000502:physiology*; D006860:Hydrogen Bonding; D007716:Kluyveromyces / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D020218:Response Elements / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000378:metabolism
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C067168:HSF1 protein, S cerevisiae; D006360:Heat-Shock Proteins; D010446:Peptide Fragments; D010710:Phosphates; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014867:Water; D004247:DNA