An adenosine-to-inosine tRNA-editing enzyme that can perform C-to-U deamination of DNA.
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.
Rubio
Mary Anne T
MA
Department of Microbiology and the Ohio State RNA Group, Ohio State University, Columbus, OH 43210, USA.
Pastar
Irena
I
Gaston
Kirk W
KW
Ragone
Frank L
FL
Janzen
Christian J
CJ
Cross
George A M
GA
Papavasiliou
F Nina
FN
Alfonzo
Juan D
JD
D000241:Adenosine / Q000378:metabolism; D000243:Adenosine Deaminase / Q000502:physiology*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D003562:Cytidine / Q000378:metabolism; D003564:Cytidine Deaminase / Q000502:physiology*; D003641:Deamination; D007288:Inosine / Q000378:metabolism; D008969:Molecular Sequence Data; D017393:RNA Editing; D034622:RNA Interference; D014529:Uridine / Q000378:metabolism
D007288:Inosine; D003562:Cytidine; D000243:Adenosine Deaminase; D003564:Cytidine Deaminase; D000241:Adenosine; D014529:Uridine