An adenosine-to-inosine tRNA-editing enzyme that can perform C-to-U deamination of DNA

Mary Anne T. Rubio, Irena Pastar, Kirk W. Gaston, Frank L. Ragone, Christian J. Janzen, George A.M. Cross, F. Nina Papavasiliou, Juan D. Alfonzo

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

Adenosine-to-inosine editing in the anticodon of tRNAs is essential for viability. Enzymes mediating tRNA adenosine deamination in bacteria and yeast contain cytidine deaminase-conserved motifs, suggesting an evolutionary link between the two reactions. In trypanosomatids, tRNAs undergo both cytidine-to-uridine and adenosine-to-inosine editing, but the relationship between the two reactions is unclear. Here we show that down-regulation of the Trypanosoma brucei tRNA-editing enzyme by RNAi leads to a reduction in both C-to-U and A-to-I editing of tRNA in vivo. Surprisingly, in vitro, this enzyme can mediate A-to-I editing of tRNA and C-to-U deamination of ssDNA but not both in either substrate. The ability to use both DNA and RNA provides a model for a multispecificity editing enzyme. Notably, the ability of a single enzyme to perform two different deamination reactions also suggests that this enzyme still maintains specificities that would have been found in the ancestor deaminase, providing a first line of evidence for the evolution of editing deaminases.

Original languageEnglish (US)
Pages (from-to)7821-7826
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume104
Issue number19
DOIs
StatePublished - May 8 2007
Externally publishedYes

Keywords

  • Deaminases
  • Decoding
  • Evolution
  • Hypermutation
  • Modification

ASJC Scopus subject areas

  • General

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