title: Evidence that the nucleic acid base queuine is incorporated intact into tRNA by animal cells.
abstract: Queuine (the base of queuosine, Q) catalytically reduced with tritium or deuterium yields a derivative in which the proton at C-8 (purine numbering system) has been exchanged and the cyclopentene ring has been reduced to a cyclopentane ring. Mouse fibroblast tRNA has been labeled by culturing the cells in medium supplemented with [3H]- and [2H]dihydroqueuine. Such tRNA yields, upon hydrolysis, the nucleoside dihydroqueuosine and a saccharide derivative of dihydroqueuosine. Each product has been identified unambiguously by mass spectrometry and chromatography. Both the 3H- and 2H-labeled material coeluted, and no unlabeled Q nucleoside was found. Therefore, dihydroqueuine is incorporated intact into tRNA in mammalian cells. Furthermore, fractionation of the labeled tRNA on concanavalin A-agarose, which specifically binds the mannosyl-Q-containing tRNAAsp, has shown that the dihydroqueuosine-containing tRNAAsp is mannosylated. This is the first direct evidence that queuine is incorporated intact into mammalian tRNA in vivo.
mesh_terms: D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D008358:Mannose / Q000378:metabolism; D013058:Mass Spectrometry; D051379:Mice; D011247:Pregnancy; D012343:RNA, Transfer / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism
chemical_list: D012346:RNA, Transfer, Amino Acyl; C037772:tRNA, dihydroqueuine-; D006147:Guanine; C019549:queuine; D012343:RNA, Transfer; D008358:Mannose