Trypanosoma brucei U insertion and U deletion activities co-purify with an enzymatic editing complex but are differentially optimized. Academic Article uri icon


  • RNA editing, the processing that generates functional mRNAs in trypanosome mitochondria, involves cycles of protein catalyzed reactions that specifically insert or delete U residues. We recently reported purification from Trypanosoma brucei mitochondria of a complex showing seven major polypeptides which exhibits the enzymatic activities inferred in editing and that a pool of fractions of the complex catalyzed U deletion, the minor form of RNA editing in vivo . We now show that U insertion activity, the major form of RNA editing in vivo , chromatographically co-purifies with both U deletion activity and the protein complex. Furthermore, these editing activities co-sediment at approximately 20 S. U insertion does not require a larger, less characterized complex, as has been suggested and could have implied that the editing machinery would not function in a processive manner. We also show that U insertion is optimized at rather different and more exacting reaction conditions than U deletion. By markedly reducing ATP and carrier RNA and increasing UTP and carrier protein relative to standard editing conditions, U insertion activity of the purified fraction is enhanced approximately 100-fold.

published proceedings

  • Nucleic Acids Res

author list (cited authors)

  • Cruz-Reyes, J., Rusch, L. N., & Sollner-Webb, B.

citation count

  • 34

complete list of authors

  • Cruz-Reyes, J||Rusché, LN||Sollner-Webb, B

publication date

  • August 1998