title: SUMOylation of GTF2IRD1 regulates protein partner interactions and ubiquitin-mediated degradation.
abstract: GTF2IRD1 is one of the genes implicated in Williams-Beuren syndrome, a disease caused by haploinsufficiency of certain dosage-sensitive genes within a hemizygous microdeletion of chromosome 7. GTF2IRD1 is a prime candidate for some of the major features of the disease, presumably caused by abnormally reduced abundance of this putative transcriptional repressor protein. GTF2IRD1 has been shown to interact with the E3 SUMO ligase PIASxβ, but the significance of this relationship is largely unexplored. Here, we demonstrate that GTF2IRD1 can be SUMOylated by the SUMO E2 ligase UBC9 and the level of SUMOylation is enhanced by PIASxβ. A major SUMOylation site was mapped to lysine 495 within a conserved SUMO consensus motif. SUMOylation of GTF2IRD1 alters the affinity of the protein for binding partners that contain SUMO-interacting motifs, including a novel family member of the HDAC repressor complex, ZMYM5, and PIASxβ itself. In addition, we show that GTF2IRD1 is targeted for ubiquitination and proteasomal degradation. Cross regulation by SUMOylation modulates this process, thus potentially regulating the level of GTF2IRD1 protein in the cell. These findings, concerning post-translational control over the activity and stability of GTF2IRD1, together with previous work showing how GTF2IRD1 directly regulates its own transcription levels suggest an evolutionary requirement for fine control over GTF2IRD1 activity in the cell.
authors.affiliation: Neuromuscular and Regenerative Medicine Unit, School of Medical Sciences, The University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Widagdo
authors.forename: Kylie M
authors.initials: KM
authors.lastname: Taylor
authors.forename: Peter W
authors.initials: PW
authors.lastname: Gunning
authors.forename: Edna C
authors.initials: EC
authors.lastname: Hardeman
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Palmer
mesh_terms: D020816:Amino Acid Motifs; D001665:Binding Sites; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D008239:Lysine / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D050828:Protein Inhibitors of Activated STAT / Q000378:metabolism / Q000502:physiology; D059748:Proteolysis; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D058207:Sumoylation; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism / Q000502:physiology; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: C405493:GTF2IRD1 protein, human; D009124:Muscle Proteins; D009687:Nuclear Proteins; C501001:PIAS2 protein, human; D050828:Protein Inhibitors of Activated STAT; D015534:Trans-Activators; D025801:Ubiquitin; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9; D008239:Lysine