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Mechanistic Studies of the tRNA-Modifying Enzyme QueA: A Chemical Imperative for the Use of AdoMet as a “Ribosyl” Donor
journal contribution
posted on 2000-04-07, 00:00 authored by Sylvia Daoud Kinzie, Bernd Thern, Dirk Iwata-ReuylThe enzyme S-adenosylmethionine:tRNA ribosyltransferase-isomerase (QueA) catalyzes the penultimate step in the biosynthesis of the tRNA
nucleoside queuosine, a unique ribosyl transfer from the cofactor S-adenosylmethionine (AdoMet) to a modified-tRNA precursor. The use of
AdoMet in this way is fundamentally new to the chemistry of this important biological cofactor. We report here the first mechanistic studies
of this remarkable enzyme, and we propose a chemical mechanism for the reaction consistent with our experimental observations.