Trypanosome telomeres are protected by a homologue of mammalian TRF2

Mol Cell Biol. 2005 Jun;25(12):5011-21. doi: 10.1128/MCB.25.12.5011-5021.2005.


Putative TTAGGG repeat-binding factor (TRF) homologues in the genomes of Trypanosoma brucei, Trypanosoma cruzi, and Leishmania major were identified. They have significant sequence similarity to higher eukaryotic TRFs in their C-terminal DNA-binding myb domains but only weak similarity in their N-terminal domains. T. brucei TRF (tbTRF) is essential and was shown to bind to duplex TTAGGG repeats. The RNA interference-mediated knockdown of tbTRF arrested bloodstream cells at G(2)/M and procyclic cells partly at S phase. Functionally, tbTRF resembles mammalian TRF2 more than TRF1, as knockdown diminished telomere single-stranded G-overhang signals. This suggests that tbTRF, like vertebrate TRF2, is essential for telomere end protection, and this also supports the hypothesis that TRF rather than Rap1 is the more ancient DNA-binding component of the telomere protein complex. Identification of the first T. brucei telomere DNA-binding protein and characterization of its function provide a new route to explore the roles of telomeres in pathogenesis of this organism. This work also establishes T. brucei as an attractive model for telomere biology.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cell Cycle / physiology
  • Humans
  • In Situ Hybridization, Fluorescence
  • Molecular Sequence Data
  • Protein Binding
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism*
  • RNA Interference
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Telomere / metabolism*
  • Telomeric Repeat Binding Protein 2 / genetics
  • Telomeric Repeat Binding Protein 2 / metabolism*
  • Trypanosoma / genetics*
  • Trypanosoma / metabolism


  • Protein Isoforms
  • Recombinant Fusion Proteins
  • Telomeric Repeat Binding Protein 2