Abstract
Methylation of histone tails plays an important role in chromatin structure and function. Previously, we reported that ESET/SETDB1 is a histone methyltransferase (HMTase). Here, we show that SETDB1 tightly associates with the human homolog of mAM, a murine ATFa-associated factor. Although recombinant ESET can methylate lysine 9 of histone H3 (H3-K9), its activity is severely compromised when compared to that of the ESET/mAM complex. mAM stimulates ESET enzymatic activity by increasing the Vmax and decreasing the Km. Importantly, mAM facilitates the ESET-dependent conversion of dimethyl H3-K9 to the trimethyl state both in vitro and in vivo. Chromatin-based transcription and ChIP analyses demonstrate that mAM enhances ESET-mediated transcriptional repression in a SAM-dependent manner, and this repression correlates with H3-K9 trimethylation at the promoter. Thus, our studies establish that promoter H3-K9 trimethylation is the cause of transcriptional repression and that mAM/hAM facilitates conversion of H3-K9 dimethyl to trimethyl by ESET/SETDB1.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Binding Sites
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Blotting, Western
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Cell Line
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Chromatin / metabolism
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Dose-Response Relationship, Drug
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Electrophoresis, Polyacrylamide Gel
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Enzymes / pharmacology
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HeLa Cells
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Histone Methyltransferases
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Histone-Lysine N-Methyltransferase*
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Histones / metabolism*
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Humans
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Kinetics
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Lysine / chemistry
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Methylation
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Methyltransferases / metabolism*
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Mice
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Molecular Sequence Data
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Precipitin Tests
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Promoter Regions, Genetic
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Protein Binding
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Protein Methyltransferases
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RNA Interference
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Recombinant Proteins / metabolism
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Repressor Proteins / metabolism
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Repressor Proteins / physiology*
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Silver Staining
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Substrate Specificity
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Time Factors
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Transcription Factors / metabolism
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Transcription Factors / physiology*
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Transcription, Genetic*
Substances
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Atf7ip protein, mouse
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Chromatin
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Enzymes
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Histones
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Recombinant Proteins
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Repressor Proteins
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Transcription Factors
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Histone Methyltransferases
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Methyltransferases
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Protein Methyltransferases
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Histone-Lysine N-Methyltransferase
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Lysine