S. Yokobori et S. Paabo, TRANSFER-RNA EDITING IN LAND SNAIL MITOCHONDRIA, Proceedings of the National Academy of Sciences of the United Statesof America, 92(22), 1995, pp. 10432-10435
Some mitochondrial tRNA genes of land snails show mismatches in the ac
ceptor stems predicted from their gene sequences. The majority of thes
e mismatches fall in regions where the tRNA genes overlap with adjacen
t down-stream genes. We have synthesized cDNA from four circularized t
RNAs and determined the sequences of the 5' and 3' parts of their acce
ptor stems. Three of the four tRNAs differ from their corresponding ge
nes at a total of 13 positions, which all fall in the 3' part of the a
cceptor stems as well as the discriminator bases. The editing events d
etected involve changes from cytidine, thymidine, and guanosine to ade
nosine residues, which generally restore base-pairing in the stems. Ho
wever, in one case an A-A mismatch is created from an A-C mismatch. It
is suggested that this form of RNA editing may involve polyadenylylat
ion of the maturing tRNAs as an intermediate.