ASCIDIAN MITOCHONDRIAL TRNA(MET) POSSESSING UNIQUE STRUCTURAL CHARACTERISTICS

Methionine tRNA was purified from muscle mitochondria of the ascidian Halocynthia roretzi and its RNA sequence was determined. Analysis of t he nucleotide sequence revealed that unlike most metazoan mitochondria l tRNAs(Met), which have a highly conserved cytidine (C) or C-derivati ve at the wobble position, the H. roretzi mitochondrial tRNA(Met) poss esses 5-carboxymethylaminomethyluridine (cmnm(5)U) at the first positi on of the anticodon. This is the first report of a single mitochondria l tRNA(Met) species having uridine (U) or a U-derivative at the wobble position.