SUMO modification enhances p66-mediated transcriptional repression of the Mi-2/NuRD complex.
Human p66alpha and p66beta are two potent transcriptional repressors that interact with the methyl-CpG-binding domain proteins MBD2 and MBD3. An analysis of the molecular mechanisms mediating repression resulted in the identification of two major repression domains in p66alpha and one in p66beta. Both p66alpha and p66beta are SUMO-modified in vivo: p66alpha at two sites (Lys-30 and Lys-487) and p66beta at one site (Lys-33). Expression of SUMO1 enhanced the transcriptional repression activity of Gal-p66alpha and Gal-p66beta. Mutation of the SUMO modification sites or using a SUMO1 mutant or a dominant negative Ubc9 ligase resulted in a significant decrease of the transcriptional repression of p66alpha and p66beta. The Mi-2/NuRD components MBD3, RbAp46, RbAp48, and HDAC1 were found to bind to both p66alpha and p66beta in vivo. Most of the interactions were not affected by the SUMO site mutations in p66alpha or p66beta, with two exceptions. HDAC1 binding to p66alpha was lost in the case of a p66alphaK30R mutant, and RbAp46 binding was reduced in the case of a p66betaK33R mutant. These results suggest that interactions within the Mi-2/NuRD complex as well as optimal repression are mediated by SUMOylation.
Gong
Zihua
Z
Institute for Genetics, Justus Liebig University Giessen, Heinrich-Buff-Ring 58-62, D-35392 Giessen, Germany.
Brackertz
Marc
M
Renkawitz
Rainer
R
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D018899:CpG Islands; D019175:DNA Methylation; D006655:Histone Deacetylases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex; D051379:Mice; D046912:Multiprotein Complexes; D016297:Mutagenesis, Site-Directed; D041681:NIH 3T3 Cells; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
C468769:GATAD2A protein, human; C468770:GATAD2B protein, human; D046912:Multiprotein Complexes; D011994:Recombinant Proteins; D012097:Repressor Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D006655:Histone Deacetylases; D056245:Mi-2 Nucleosome Remodeling and Deacetylase Complex