Unusual usage of wobble modifications in mitochondrial tRNAs of the nematode Ascaris suum

To understand the decoding property of nematode mitochondrial tRNAs with unusual secondary structures, post-transcriptional modifications at wobble positions of Ascaris suum mitochondrial tRNAs corresponding to two-codon families ending with a purine were analyzed. 5-Carboxymethylaminomethyluridine (cmnm(5)U) was identified at the wobble positions of tRNA(Lys), tRNA(Glu) and tRNA(Gln), while 5-carboxymethylaminomethyl-2-thiouridine (cmnm(5)s(2)U) was present in tRNA(UAA)(Leu) and tRNA(Trp). In most bacterial and mitochondrial tRNAs, the 2-thiouridine derivative is present in tRNAs for Lys, Gin and Gln. These is no report that cmnm(5)s(2)U is used in tRNALeu and tRNA(Trp). The unusual usage of wobble modifications might assist decoding of nematode mitochondrial mRNAs. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.