期刊
MOLECULAR AND CELLULAR BIOLOGY
卷 20, 期 17, 页码 6449-6465出版社
AMER SOC MICROBIOLOGY
DOI: 10.1128/MCB.20.17.6449-6465.2000
关键词
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资金
- NATIONAL CANCER INSTITUTE [T32CA009171, P01CA074294, R01CA066671, P30CA010815] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [P01DK049210] Funding Source: NIH RePORTER
- NCI NIH HHS [CA 74294, T32 CA009171, P30 CA010815, CA 66671, CA 09171, P01 CA074294] Funding Source: Medline
- NIDDK NIH HHS [P01 DK049210] Funding Source: Medline
The KRAB domain is a highly conserved transcription repression module commonly found in eukaryotic zinc finger proteins. KRAB-mediated repression requires binding to the KAP-1 corepressor, which in turn recruits members of the heterochromatin protein 1 (HP1) family. The HPI proteins are nonhistone chromosomal proteins, although it is unclear how they are targeted to unique chromosomal domains or promoters. In this report, we have reconstituted and characterized the HP1-KAP-1 interaction using purified proteins and have compared KAP-1 to three other known HP1 binding proteins: SP100, lamin B receptor (LBR), and the p150 subunit from chromatin assembly factor (CAF-1 p150), We show that the chromoshadow domain (CSD) of HP1 is a potent repression domain that binds directly to all four previously described proteins. For KAP-1, we have mapped the CSD interaction region to a 15-amino-acid segment, termed the HP1BD, which is also present in CAF-1 p150 but not SP100 or LBR, The region of KAP-1 harboring the HP1BD binds as a monomer to a dimer of the CSD, as revealed by gel filtration, analytical ultracentrifugation, and optical biosensor analyses. The use of a spectrum of amino acid substitutions in the human HP1 alpha CSD revealed a strong correlation between CSD-mediated repression and binding to KAP-1, CAF-1 p150, and SP100 but not LBR, Differences among the HP1 binding partners could also be discerned by fusion to a heterologous DNA binding domain and by the potential to act as dominant negative molecules. Together, these results strongly suggest that KAP-1 is a physiologically relevant target for HP1 function.
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