This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Amino Acids Biosynthesis → Proteinogenic Amino Acids Biosynthesis → L-selenocysteine Biosynthesis|
Some taxa known to possess this pathway include : Escherichia coli K-12 substr. MG1655
Expected Taxonomic Range: Bacteria
Selenocysteine has been called the 21st amino acid. It is an essential constituent of 3 proteins in E. coli : formic dehydrogenases, FDHO, FDHN, and FDHH; each of them contains one selenocysteine residue. The biosynthesis of selenocysteine is unique among amino acid biosyntheses because its defining step occurs while attached to a tRNA molecule. The tRNA molecule, tRNA,sec, serves only to insert selenocysteine into these proteins. tRNAsec has an anticodon that recognizes the stop codon UGA; it also has properties that allow it to be charged with serine by serS-encoded seryl-tRNA synthetase. But it cannot insert serine at an UGA codon. Only after it has been converted to selenocysteyl-tRNAsec by the action of selenocysteine synthetase can it recognize certain UGAs as sense codons and insert selenocysteine there. Recognition of UGA as a sense codon and insertion of selenocysteine depends on adjacent sequences in mRNA termed SECIS (selenocysteine insertion sequence) and a special elongation factor termed SELB, the product of selB, which acts in place of EF-Tu in this special case..
Selenophosphate donates selenium to seryl-tRNAsec thereby converting it to selenocysteyl-tRNAsec. The physiological source of its selenium, shown here as selenide, is not known for certain. Selenide is synthesized, via selinite, from selenate by the same enzymes that reduce sulfate,via sulfite, to sulfide.
Unification Links: EcoCyc:PWY0-901
Relationship Links: KEGG:PART-OF:map00970
Baron90: Baron C, Heider J, Bock A (1990). "Mutagenesis of selC, the gene for the selenocysteine-inserting tRNA-species in E. coli: effects on in vivo function." Nucleic Acids Res 18(23);6761-6. PMID: 1702199
Engelhardt92: Engelhardt H, Forchhammer K, Muller S, Goldie KN, Bock A (1992). "Structure of selenocysteine synthase from Escherichia coli and location of tRNA in the seryl-tRNA(sec)-enzyme complex." Mol Microbiol 6(23);3461-7. PMID: 1474891
Heider92: Heider J, Baron C, Bock A (1992). "Coding from a distance: dissection of the mRNA determinants required for the incorporation of selenocysteine into protein." EMBO J 11(10);3759-66. PMID: 1396569
Zinoni86: Zinoni F, Birkmann A, Stadtman TC, Bock A (1986). "Nucleotide sequence and expression of the selenocysteine-containing polypeptide of formate dehydrogenase (formate-hydrogen-lyase-linked) from Escherichia coli." Proc Natl Acad Sci U S A 1986;83(13);4650-4. PMID: 2941757
Asahara94: Asahara H, Himeno H, Tamura K, Nameki N, Hasegawa T, Shimizu M (1994). "Escherichia coli seryl-tRNA synthetase recognizes tRNA(Ser) by its characteristic tertiary structure." J Mol Biol 236(3);738-48. PMID: 8114091
Baron91: Baron C, Bock A (1991). "The length of the aminoacyl-acceptor stem of the selenocysteine-specific tRNA(Sec) of Escherichia coli is the determinant for binding to elongation factors SELB or Tu." J Biol Chem 266(30);20375-9. PMID: 1939093
Baron93a: Baron C, Westhof E, Bock A, Giege R (1993). "Solution structure of selenocysteine-inserting tRNA(Sec) from Escherichia coli. Comparison with canonical tRNA(Ser)." J Mol Biol 231(2);274-92. PMID: 8510147
Berg91a: Berg BL, Baron C, Stewart V (1991). "Nitrate-inducible formate dehydrogenase in Escherichia coli K-12. II. Evidence that a mRNA stem-loop structure is essential for decoding opal (UGA) as selenocysteine." J Biol Chem 266(33);22386-91. PMID: 1834670
Bilokapic04: Bilokapic S, Korencic D, Soll D, Weygand-Durasevic I (2004). "The unusual methanogenic seryl-tRNA synthetase recognizes tRNASer species from all three kingdoms of life." Eur J Biochem 271(4);694-702. PMID: 14764085
Borel94: Borel F, Vincent C, Leberman R, Hartlein M (1994). "Seryl-tRNA synthetase from Escherichia coli: implication of its N-terminal domain in aminoacylation activity and specificity." Nucleic Acids Res 22(15);2963-9. PMID: 8065908
Cusack90: Cusack S, Berthet-Colominas C, Hartlein M, Nassar N, Leberman R (1990). "A second class of synthetase structure revealed by X-ray analysis of Escherichia coli seryl-tRNA synthetase at 2.5 A." Nature 347(6290);249-55. PMID: 2205803
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Ehrenreich92: Ehrenreich A, Forchhammer K, Tormay P, Veprek B, Bock A (1992). "Selenoprotein synthesis in E. coli. Purification and characterisation of the enzyme catalysing selenium activation." Eur J Biochem 206(3);767-73. PMID: 1606960
Eriani90a: Eriani G, Delarue M, Poch O, Gangloff J, Moras D (1990). "Partition of tRNA synthetases into two classes based on mutually exclusive sets of sequence motifs." Nature 347(6289);203-6. PMID: 2203971
Forchhammer89: Forchhammer K, Leinfelder W, Bock A (1989). "Identification of a novel translation factor necessary for the incorporation of selenocysteine into protein." Nature 342(6248);453-6. PMID: 2531290
Forchhammer91: Forchhammer K, Boesmiller K, Bock A (1991). "The function of selenocysteine synthase and SELB in the synthesis and incorporation of selenocysteine." Biochimie 73(12);1481-6. PMID: 1839607
Forchhammer91a: Forchhammer K, Leinfelder W, Boesmiller K, Veprek B, Bock A (1991). "Selenocysteine synthase from Escherichia coli. Nucleotide sequence of the gene (selA) and purification of the protein." J Biol Chem 266(10);6318-23. PMID: 2007584
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