Two novel Krüppel-associated box-containing zinc-finger proteins, KRAZ1 and KRAZ2, repress transcription through functional interaction with the corepressor KAP-1 (TIF1beta/KRIP-1).
We have isolated two novel Krüppel-like zinc finger proteins containing the evolutionarily conserved Krüppel-associated box (KRAB), KRAZ1 and KRAZ2, and demonstrated that they repress transcription when heterologously targeted to DNA. Their repression activity appeared to be mediated by the putative corepressor KAP-1 (KRAB-associated protein-1), because KRAZ1/2 bind to KAP-1, but KRAB mutants of KRAZ1/2 that are unable to interact with KAP-1 lack repression activity, and KAP-1 has intrinsic repressor activity and potentiates KRAZ1/2-mediated repression. We dissected the KAP-1 protein into a KRAB-interacting domain and a region necessary for repression. Using a mammalian two-hybrid assay, we further demonstrated that KAP-1 deletions lacking repression activity fused to the VP16 transactivation domain strongly activated transcription when coexpressed with KRAZ1. In contrast, VP16-KAP-1 fusions retaining repression activity resulted in repression. These results provide the first evidence that KAP-1 functionally interacts with KRAB in mammalian cells and seems to exert repressor activity in the DNA-bound KRAB-KAP-1 complex, and they further support the hypothesis that KAP-1 functions as a corepressor for the large class of KRAB-containing zinc finger proteins.
Agata
Y
Y
Center for Molecular Biology and Genetics, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Matsuda
E
E
Shimizu
A
A
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051741:Kruppel-Like Transcription Factors; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010449:Peptide Mapping; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000302:isolation & purification / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic; D000076183:Tripartite Motif-Containing Protein 28; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C109484:ZNF10 protein, human; C119653:Zfp118 protein, mouse; C119654:Zfp68 protein, mouse; C103190:Trim28 protein, mouse; D000076183:Tripartite Motif-Containing Protein 28