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Updated: May 25, 2026

Sequence-specific Labeling of Nucleic Acids and Proteins with Methyltransferases and Cofactor Analogues
Published on: November 22, 2014
Selenomodification of tRNA in archaea requires a bipartite rhodanese enzyme
Dan Su1, Temitope T Ojo, Dieter Söll
1Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
Abstract:
5-Methylaminomethyl-2-selenouridine (mnm(5)Se(2)U) is found in the first position of the anticodon in certain tRNAs from bacteria, archaea and eukaryotes. This selenonucleoside is formed in Escherichia coli from the corresponding thionucleoside mnm(5)S(2)U by the monomeric enzyme YbbB. This nucleoside is present in the tRNA of Methanococcales, yet the corresponding 2-selenouridine synthase is unknown in archaea and eukaryotes. Here we report that a bipartite ybbB ortholog is present in all members of the Methanococcales. Gene deletions in Methanococcus maripaludis and in vitro activity assays confirm that the two proteins act in trans to form in tRNA a selenonucleoside, presumably mnm(5)Se(2)U. Phylogenetic data suggest a primal origin of seleno-modified tRNAs.
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