Dh. Price et Mw. Gray, Confirmation of predicted edits and demonstration of unpredicted edits in Acanthamoeba castellanii mitochondrial tRNAs, CURR GENET, 35(1), 1999, pp. 23-29
In the amoeboid protozoon Acanthamoeba castellanii 13 of the 16 mtDNA-encod
ed tRNA sequences have mis-matches at one or more of the first three positi
ons in the acceptor stem. A previous study had indicated that these mis-mat
ches are corrected by a form of RNA editing. In the present study, the patt
ern of editing was further investigated by sequence analysis of both halves
of the acceptor stem of ii mtDNA-encoded tRNAs. The results confirm all of
the remaining editing sites predicted on the basis of the secondary struct
ure modelling of A. castellanii mitochondrial tRNAs, and identify two unexp
ected edits. We also investigated the expression and editing of transcripts
of an unusual trnX gene specifying an eight-nucleotide anticodon loop sequ
ence. Although no mature 3'-CCA(OH)-containing tRNA(X) products were detect
ed, editing was observed in some circularized tRNAX clones. The implication
s of these results with respect to the mechanism of editing and the evoluti
onary origin of this process are discussed.