mAM facilitates conversion by ESET of dimethyl to trimethyl lysine 9 of histone H3 to cause transcriptional repression

Mol Cell. 2003 Aug;12(2):475-87. doi: 10.1016/j.molcel.2003.08.007.

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

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Blotting, Western
  • Cell Line
  • Chromatin / metabolism
  • Dose-Response Relationship, Drug
  • Electrophoresis, Polyacrylamide Gel
  • Enzymes / pharmacology
  • HeLa Cells
  • Histone Methyltransferases
  • Histone-Lysine N-Methyltransferase*
  • Histones / metabolism*
  • Humans
  • Kinetics
  • Lysine / chemistry
  • Methylation
  • Methyltransferases / metabolism*
  • Mice
  • Molecular Sequence Data
  • Precipitin Tests
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Methyltransferases
  • RNA Interference
  • Recombinant Proteins / metabolism
  • Repressor Proteins / metabolism
  • Repressor Proteins / physiology*
  • Silver Staining
  • Substrate Specificity
  • Time Factors
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Transcription, Genetic*

Substances

  • Atf7ip protein, mouse
  • Chromatin
  • Enzymes
  • Histones
  • Recombinant Proteins
  • Repressor Proteins
  • Transcription Factors
  • Histone Methyltransferases
  • Methyltransferases
  • Protein Methyltransferases
  • Histone-Lysine N-Methyltransferase
  • Lysine