title: Maturation of a hypermodified nucleoside in transfer RNA.
abstract: E. coli C6 rel- met- cys- was cultured in a fully supplemented medium and in media lacking cysteine or methionine. tRNA isolated from the three cultures containted, respectively, a normal complement of modified nucleosides; a deficiency in thiolated nucleosides and a deficiency in methylated nucleosides. Both sulfur-deficient tRNA and methyl-deficient tRNA contained large amounts of N-6- (delta-2-isopentenyl) adenosine and small amounts of the 2-methylthio derivative. Methyl-deficient tRNA contained, in addition a large amount of a cytokinin active, differently modified nucleoside that is believed to be a sulfur derivative of N6-(delta-2-isopentenyl) adenosine. The structure of this compound is unknown. When methly-deficient tRNA and the precusor the tRNA-Tyr su3-+ A25 were enzymatically methylated in vitro, methyl groups were incorporated into derivatives of isopentenyladenosine. These results indicate that the biosynthesis of the 2-methylthio derivative of isopentenyladenosine may occur in a sequential manner, i.e., thiolation of isopentenyladenosine followed by methylation.
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives*; D000596:Amino Acids / Q000378:metabolism; D003470:Culture Media; D003545:Cysteine / Q000172:deficiency; D003583:Cytokinins / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism*; D008715:Methionine / Q000172:deficiency; D008745:Methylation; D009705:Nucleosides / Q000096:biosynthesis* / Q000494:pharmacology; D012329:RNA, Bacterial / Q000096:biosynthesis*; D012343:RNA, Transfer / Q000096:biosynthesis*
chemical_list: D000596:Amino Acids; D003470:Culture Media; D003583:Cytokinins; D009705:Nucleosides; D012329:RNA, Bacterial; D012343:RNA, Transfer; D008715:Methionine; D000241:Adenosine; D003545:Cysteine