Terminal deoxynucleotidyltransferase forms a ternary complex with a novel chromatin remodeling protein with 82 kDa and core histone

Genes Cells. 2003 Jun;8(6):559-71. doi: 10.1046/j.1365-2443.2003.00656.x.


Background: Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase that enhances the Ig and TcR gene diversity in the N region at the junctions of variable (V), diversity (D) and joining (J) segments in B- and T-cells. TdT synthesizes the N region in concert with many proteins including DNA-PKcs, Ku70 and Ku86. To elucidate the molecular mechanism of the N region synthesis, we first attempted to isolate the genes with products that directly interact with TdT.

Results: Using a yeast two-hybrid system, we isolated a cDNA clone encoding a novel nuclear protein that interacts with TdT. This protein was designated as TdT interacting factor 2 (TdIF2). The confined region of the C-terminal in TdIF2 is involved in specific interaction with the entire C-terminal in TdT. TdIF2 contains an acidic region comprised of 42 residues. TdIF2 was shown to bind specifically to a core histone by pull down assay using specific antibodies against TdIF2. When a TdT/TdIF2 complex was applied on to a DNA-cellulose column, only TdT bound to the column while TdIF2 passed through. TdIF2 reduces the TdT activity to 46% of its maximum value in vitro assay system using activated DNA as primer.

Conclusions: TdIF2 binds directly to TdT and core histone. Furthermore, TdT, TdIF2 and core histone form a ternary complex. TdIF2 liberates H2A/H2B from a core histone in correlation with PCNA. The enzymatic consequence of the TdIF2/TdT complex is the reduction of TdT activity in vitro. TdIF2 would function as a chromatin remodeling protein at the N region synthesis.

MeSH terms

  • Amino Acid Sequence
  • Cellulose / analogs & derivatives*
  • Cellulose / chemistry
  • Cellulose / metabolism
  • Chromatin / metabolism*
  • DNA / chemistry
  • DNA / genetics
  • DNA / metabolism
  • DNA Nucleotidylexotransferase / antagonists & inhibitors
  • DNA Nucleotidylexotransferase / genetics
  • DNA Nucleotidylexotransferase / metabolism*
  • Histones / metabolism*
  • Humans
  • Molecular Sequence Data
  • Molecular Weight
  • Nuclear Proteins / isolation & purification
  • Nuclear Proteins / metabolism*
  • Proliferating Cell Nuclear Antigen / genetics
  • Proliferating Cell Nuclear Antigen / metabolism
  • Saccharomyces cerevisiae
  • Sequence Deletion
  • Two-Hybrid System Techniques


  • Chromatin
  • DNA-cellulose
  • Histones
  • Nuclear Proteins
  • Proliferating Cell Nuclear Antigen
  • Cellulose
  • DNA
  • DNA Nucleotidylexotransferase