title: SUMO-1-dependent allosteric regulation of thymine DNA glycosylase alters subnuclear localization and CBP/p300 recruitment.
abstract: Previous studies have demonstrated that the base excision repair enzyme thymine DNA glycosylase (TDG) mediates recruitment of histone acetyltransferases CREB-binding protein (CBP) and p300 to DNA, suggesting a plausible role for these factors in TDG-mediated repair. Furthermore, TDG was found to potentiate CBP/p300-dependent transcription and serve as a substrate for CBP/p300 acetylation. Here, we show that the small ubiquitin-like modifier 1 (SUMO-1) protein binding activity of TDG is essential for activation of CBP and localization to promyelocytic leukemia protein oncogenic domains (PODs). SUMO-1 binding is mediated by two distinct amino- and carboxy-terminal motifs (residues 144 to 148 and 319 to 322) that are negatively regulated by DNA binding via an amino-terminal hydrophilic region (residues 1 to 121). TDG is also posttranslationally modified by covalent conjugation of SUMO-1 (sumoylation) to lysine 341. Interestingly, we found that sumoylation of TDG blocks interaction with CBP and prevents TDG acetylation in vitro. Furthermore, sumoylation effectively abrogates intermolecular SUMO-1 binding and a sumoylation-deficient mutant accumulates in PODs, suggesting that sumoylation negatively regulates translocation to these nuclear structures. These findings suggest that TDG sumoylation promotes intramolecular interactions with amino- and carboxy-terminal SUMO-1 binding motifs that dramatically alter the biochemical properties and subcellular localization of TDG.
authors.affiliation: Department of Physiology and Pharmacology, Siebens-Drake Medical Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada N6G 2V4.
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Mohan
authors.forename: Anita
authors.initials: A
authors.lastname: Rao
authors.forename: Jason
authors.initials: J
authors.lastname: Gagliardi
authors.forename: Marc
authors.initials: M
authors.lastname: Tini
mesh_terms: D000495:Allosteric Site; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D045744:Cell Line, Tumor; D004260:DNA Repair; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D025842:SUMO-1 Protein; D017386:Sequence Homology, Amino Acid; D025841:Small Ubiquitin-Related Modifier Proteins / Q000502:physiology*; D044502:Thymine DNA Glycosylase / Q000096:biosynthesis* / Q000502:physiology*; D014158:Transcription, Genetic; D050880:p300-CBP Transcription Factors / Q000378:metabolism*
chemical_list: D025842:SUMO-1 Protein; C495501:SUMO1 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; D050880:p300-CBP Transcription Factors; D044502:Thymine DNA Glycosylase