In vitro incorporation of selenium into tRNAs of Salmonella typhimurium.
Broken-cell preparations of Salmonella typhimurium rapidly incorporated 75Se from 75SeO3(2-) into tRNA by an ATP-dependent process. Selenium incorporation in the presence of 50 microM 75SeO3(2-) (0.8-1 pmol per A260 unit) was enhanced by the selenocysteine precursor, O-acetyl-L-serine (to 3.7 pmol per A260 unit). This increase in incorporation was a function of O-acetyl-L-serine concentration. Neither O-acetyl-L-homoserine nor O-phospho-L-serine stimulated the incorporation of selenium into tRNA. The incorporation of 75Se from 75SeO3(2-) was decreased by adding L-selenocysteine but not by adding the D isomer. When homologous bulk tRNA was added to the broken-cell preparations, an increased rate of 75Se labeling was observed. The supernatant fraction of the broken-cell preparation contained all of the enzymes required for this process. Reversed-phase HPLC analysis of labeled bulk tRNA digested to nucleosides showed the presence of a labeled compound that coeluted with authentic 5-methylaminomethyl-2-selenouridine.
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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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Politino
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Stadtman
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TC
D000255:Adenosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D012343:RNA, Transfer / Q000096:biosynthesis*; D012486:Salmonella typhimurium / Q000378:metabolism*; D012643:Selenium / Q000378:metabolism*; D012644:Selenium Radioisotopes; D012694:Serine / Q000031:analogs & derivatives / Q000378:metabolism
D012644:Selenium Radioisotopes; D012694:Serine; D000255:Adenosine Triphosphate; D012343:RNA, Transfer; C043943:O-acetylserine; D012643:Selenium