Utilization of selenocysteine as a source of selenium for selenophosphate biosynthesis.
Selenophosphate synthetase (SPS), the selD gene product from Escherichia coli, catalyzes the biosynthesis of monoselenophosphate from selenide and ATP. Characterization of selenophosphate synthetase revealed the determined K(m) value for selenide is far above the optimal concentration needed for growth and approached levels which are toxic. Selenocysteine lyase enzymes, which decompose selenocysteine to elemental selenium (Se(0)) and alanine, were considered as candidates for the control of free selenium levels in vivo. The ability of a lyase protein to generate Se(0) in the proximity of SPS maybe an attractive solution to selenium toxicity as well as the high K(m) value for selenide. Recently, three E. coli NifS-like proteins, CsdB, CSD, and IscS, were characterized. All three proteins exhibit lyase activity on L-cysteine and L-selenocysteine and produce sulfane sulfur, S(0), or Se(0) respectively. Each lyase can effectively mobilize Se(0) from L-selenocysteine for selenophosphate biosynthesis.
Lacourciere
G M
GM
Laboratory of Biochemistry, National Institutes of Health, NHLBI, 50 South Drive, Room 2126, Bethesda, MD 20892, USA. lacourcg@nhlbi.nih.gov
Stadtman
T C
TC
D000255:Adenosine Triphosphate / Q000378:metabolism; D013437:Carbon-Sulfur Lyases / Q000378:metabolism; D029721:Drosophila Proteins; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D008190:Lyases / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010770:Phosphotransferases / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D011506:Proteins; D012643:Selenium / Q000378:metabolism* / Q000494:pharmacology; D018036:Selenium Compounds / Q000378:metabolism*; D017279:Selenocysteine / Q000378:metabolism*; D051140:Selenoproteins
D029721:Drosophila Proteins; D010710:Phosphates; D011506:Proteins; D018036:Selenium Compounds; D051140:Selenoproteins; D017279:Selenocysteine; C076818:selenophosphate; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; C062762:selenophosphate synthetase; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; C034278:selenocysteine lyase; D012643:Selenium