Inhibition of DNA binding by differential sumoylation of heat shock factors.
Covalent modification of proteins by the small ubiquitin-related modifier SUMO regulates diverse biological functions. Sumoylation usually requires a consensus tetrapeptide, through which the binding of the SUMO-conjugating enzyme Ubc9 to the target protein is directed. However, additional specificity determinants are in many cases required. To gain insights into SUMO substrate selection, we have utilized the differential sumoylation of highly similar loop structures within the DNA-binding domains of heat shock transcription factor 1 (HSF1) and HSF2. Site-specific mutagenesis in combination with molecular modeling revealed that the sumoylation specificity is determined by several amino acids near the consensus site, which are likely to present the SUMO consensus motif to Ubc9. Importantly, we also demonstrate that sumoylation of the HSF2 loop impedes HSF2 DNA-binding activity, without affecting its oligomerization. Hence, SUMO modification of the HSF2 loop contributes to HSF-specific regulation of DNA binding and broadens the concept of sumoylation in the negative regulation of gene expression.
Anckar
Julius
J
Turku Centre for Biotechnology, P.O. Box 123, FI-20521 Turku, Finland.
Hietakangas
Ville
V
Denessiouk
Konstantin
K
Thiele
Dennis J
DJ
Johnson
Mark S
MS
Sistonen
Lea
L
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D014157:Transcription Factors; C070389:HSF2 protein, human; D004247:DNA; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9