title: Distribution of cytokinin-active nucleosides in isoaccepting transfer ribonucleic acids from Agrobacterium tumefaciens.
abstract: The cytokinin-active isoprenoid nucleosides of Agrobacterium tumefaciens transfer ribonucleic acid were identified by high-pressure liquid chromatography, permethylation, and mass spectroscopy. Besides the expected 6-[(3-methylbut-2-enyl)amino]-9-(beta-D-ribofuranosyl)purine (i6A) and its 2-methylthio derivative (ms2i6A), substantial amounts of cis- and trans-ribosylzeatin (io6A) and cis-2-(methylthio)ribosylzeatin (c-ms2io6A) were present. These hydroxylated side chain derivatives are normally characteristic of plant tRNA. Fractionation of the total bacterial tRNA on BD-cellulose and RPC-5 allowed isolation of purified iso-accepting species whose cytokinin nucleoside contents were then determined. Distribution of the isoprenoid nucleosides among the U-group tRNA species was not uniform. cis-Ribosylzeatin was found almost exclusively in one tRNASer while ms2io6A was found predominantly in tRNAPhe, tRNASer, and tRNATyr. Not all cytokinin-active species were found in every member of the U-group tRNAs. The only species present in tRNATrp was i6A; it contained no zeatin derivatives. The hydroxylation and methylthiolation processes appear to be highly specific and dependent upon tRNA structure or sequence.
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D002852:Chromatography, Ion Exchange; D003583:Cytokinins / Q000494:pharmacology; D013058:Mass Spectrometry; D010937:Plant Growth Regulators / Q000494:pharmacology; D012343:RNA, Transfer / Q000302:isolation & purification*; D012231:Rhizobium / Q000032:analysis* / Q000201:enzymology; D012263:Ribonucleosides / Q000032:analysis*
chemical_list: D003583:Cytokinins; D010937:Plant Growth Regulators; D012263:Ribonucleosides; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases