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Biosynthesis of Selenium-Modified tRNAs in Methanococcus vannielii
Michael Politino, Lin Tsai, Zsuzsa Veres and Thressa C. Stadtman
Proceedings of the National Academy of Sciences of the United States of America
Vol. 87, No. 16 (Aug., 1990), pp. 6345-6348
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/2356204
Page Count: 4
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Selenium-containing nucleosides are natural components of several tRNA species in Methanococcus vannielii. In the present study, the incorporation of selenium from 75SeO2- 3 into these macromolecules was investigated in sonic extracts of M. vannielii. Nucleoside analysis of the 75Se-labeled tRNAs from these in vitro reaction mixtures demonstrated that the selenium was present in 75Se-labeled nucleosides identical to the two naturally occurring 2-selenouridines produced in vivo. Incorporation of selenium into these nucleosides was ATP-dependent and was maximal after 20 min. Addition of O-acetylserine enhanced the activity 2- to 3-fold, implicating a role for selenocysteine in the reaction. Added L-selenocysteine could function as a selenium donor, but the D isomer and DL-selenomethionine were inactive. RPC-5 chromatography of bulk tRNA isolated from M. vannielii grown on 75SeO2- 3 separated five major species of seleno-tRNAs. The amino acid-accepting activity of these tRNAs was investigated.
Proceedings of the National Academy of Sciences of the United States of America © 1990 National Academy of Sciences