title: Alterations of tRNA modification in mammalian systems: the effect of ethionine.
abstract: The relationship between the modification of tRNA and its ability to act as a substrate for homologous tRNA modification enzymes in vitro was studied. The tRNA extracted from the livers of rats was active as a substrate for in vitro methylation with extracts from normal rat liver 19 h after treatment with L-ethionine (35 mg/100 g/24 h). After 4 weeks of feeding a diet containing o.25% DL-ethionine, the tRNA was a poor substrate for methylation in vitro, even though it was deficient in methylated nucleosides. Only 18% and 7% of the available sites could be methylated after 67 h and 4 weeks, respectively, of ethionine treatment. 3-(3-amino-3-carboxypropyl)uridine, a nucleoside that is also synthesized from S-adenosylmethionine, was assayed in individual tRNAs by their reactivity with the N-hydroxysuccinimide ester of phenoxyacetic acid. The reactivity of tRNAIle, tRNAAsn, and tRNAThr was decreased by treatment with ethionine at 67 h as well as at 2 and 4 weeks, although no difference could be detected at 19 h.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D004926:Escherichia coli; D005001:Ethionine / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D012343:RNA, Transfer / Q000378:metabolism*; D051381:Rats; D012263:Ribonucleosides / Q000032:analysis; D013329:Structure-Activity Relationship; D012359:tRNA Methyltransferases / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D012263:Ribonucleosides; D012343:RNA, Transfer; D012359:tRNA Methyltransferases; D005001:Ethionine