MetaCyc Pathway: L-selenocysteine biosynthesis I (bacteria)
Inferred from experiment

Pathway diagram: L-selenocysteine biosynthesis I (bacteria)

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: BiosynthesisAmino Acids BiosynthesisProteinogenic Amino Acids BiosynthesisL-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.

[Engelhardt92], [Zinoni86] , [Heider92] , [Baron93], [Baron90] review: Boeck, A and M. Thanbichler, Selenocysteine. EcoSal,

Citations: [Stadtman96]

Variants: L-selenocysteine biosynthesis II (archaea and eukaryotes)

Unification Links: EcoCyc:PWY0-901

Relationship Links: KEGG:PART-OF:map00970

Created 12-Feb-2004 by Ingraham JL, UC Davis


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

Baron93: Baron C, Heider J, Bock A (1993). "Interaction of translation factor SELB with the formate dehydrogenase H selenopolypeptide mRNA." Proc Natl Acad Sci U S A 90(9);4181-5. PMID: 8483932

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

Stadtman96: Stadtman TC (1996). "Selenocysteine." Annu Rev Biochem 65;83-100. PMID: 8811175

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

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Airas07: Airas RK (2007). "Magnesium dependence of the measured equilibrium constants of aminoacyl-tRNA synthetases." Biophys Chem 131(1-3);29-35. PMID: 17889423

Asahara93: Asahara H, Himeno H, Tamura K, Nameki N, Hasegawa T, Shimizu M (1993). "Discrimination among E. coli tRNAs with a long variable arm." Nucleic Acids Symp Ser (29);207-8. PMID: 7504246

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

Berg91: 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

BRENDA14: BRENDA team (2014). Imported from BRENDA version existing on Aug 2014.

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

Cusack91: Cusack S, Hartlein M, Leberman R (1991). "Sequence, structural and evolutionary relationships between class 2 aminoacyl-tRNA synthetases." Nucleic Acids Res 19(13);3489-98. PMID: 1852601

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

Easton06: Easton JA, Thompson P, Crowder MW (2006). "Time-dependent translational response of E. coli to excess Zn(II)." J Biomol Tech 17(5);303-7. PMID: 17122063

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

Eriani90: 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

Forchhammer91b: Forchhammer K, Bock A (1991). "Selenocysteine synthase from Escherichia coli. Analysis of the reaction sequence." J Biol Chem 266(10);6324-8. PMID: 2007585

Forster90: Forster C, Ott G, Forchhammer K, Sprinzl M (1990). "Interaction of a selenocysteine-incorporating tRNA with elongation factor Tu from E.coli." Nucleic Acids Res 18(3);487-91. PMID: 2408012

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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