Selenium is mobilized in vivo from free selenocysteine and is incorporated specifically into formate dehydrogenase H and tRNA nucleosides.
Selenophosphate synthetase (SPS), the selD gene product from Escherichia coli, catalyzes the biosynthesis of monoselenophosphate, AMP, and orthophosphate in a 1:1:1 ratio from selenide and ATP. It was recently demonstrated that selenium delivered from selenocysteine by an E. coli NifS-like protein could replace free selenide in the in vitro SPS assay for selenophosphate formation (G. M. Lacourciere, H. Mihara, T. Kurihara, N. Esaki, and T. C. Stadtman, J. Biol. Chem. 275:23769-23773, 2000). During growth of E. coli in the presence of 0.1 microM (75)SeO(3)(2-) and increasing amounts of L-selenocysteine, a concomitant decrease in (75)Se incorporation into formate dehydrogenase H and nucleosides of bulk tRNA was observed. This is consistent with the mobilization of selenium from L-selenocysteine in vivo and its use in selenophosphate formation. The ability of E. coli to utilize selenocysteine as a selenium source for selenophosphate biosynthesis in vivo supports the participation of the NifS-like proteins in selenium metabolism.
Lacourciere
Gerard M
GM
Laboratory of Biochemistry, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA. lacourcg@nhlbi.nih.gov
D001692:Biological Transport; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D005560:Formate Dehydrogenases / Q000378:metabolism*; D006864:Hydrogenase / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D012643:Selenium / Q000378:metabolism*; D018036:Selenium Compounds / Q000378:metabolism; D017279:Selenocysteine / Q000378:metabolism*
D009097:Multienzyme Complexes; D010710:Phosphates; D018036:Selenium Compounds; D017279:Selenocysteine; C076818:selenophosphate; D012343:RNA, Transfer; D006864:Hydrogenase; D005560:Formate Dehydrogenases; C054017:formate hydrogenlyase; D012643:Selenium