Biosynthesis of selenium-modified tRNAs in Methanococcus vannielii.
Selenium-containing nucleosides are natural components of several tRNA species in Methanococcus vannielii. In the present study, the incorporation of selenium from 75SeO3(2-) 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 75SeO3(2-) separated five major species of seleno-tRNAs. The amino acid-accepting activity of these tRNAs was investigated.
Politino
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Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
Tsai
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L
Veres
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Stadtman
T C
TC
D000596:Amino Acids / Q000378:metabolism; D002250:Carbon Radioisotopes; D003545:Cysteine / Q000031:analogs & derivatives / Q000378:metabolism; D019605:Euryarchaeota / Q000378:metabolism*; D007700:Kinetics; D012343:RNA, Transfer / Q000302:isolation & purification / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis; D012643:Selenium / Q000302:isolation & purification / Q000378:metabolism*; D012644:Selenium Radioisotopes; D017279:Selenocysteine; D012645:Selenomethionine / Q000378:metabolism
D000596:Amino Acids; D002250:Carbon Radioisotopes; D012346:RNA, Transfer, Amino Acyl; D012644:Selenium Radioisotopes; C366009:seleno-tRNA; D017279:Selenocysteine; D012343:RNA, Transfer; D012645:Selenomethionine; D012643:Selenium; D003545:Cysteine