EC - O-phospho-L-seryl-tRNA:Cys-tRNA synthase

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IntEnz Enzyme Nomenclature


Accepted name:
O-phospho-L-seryl-tRNA:Cys-tRNA synthase
Other names:
Sep-tRNA:Cys-tRNA synthase
Systematic name:
O-phospho-L-seryl-tRNACys:hydrogen sulfide 2-aminopropanoate transferase



In organisms like Archaeoglobus fulgidus lacking EC (cysteine—tRNA ligase) for the direct Cys-tRNACys formation, Cys-tRNACys is produced by an indirect pathway, in which EC (O-phosphoseryl—tRNA ligase) ligates O-phosphoserine to tRNACys, and EC converts the produced O-phospho-L-seryl-tRNACys to Cys-tRNACys. The SepRS/SepCysS pathway is the sole route for cysteine biosynthesis in the organism [1]. Methanosarcina mazei can use both pathways, the direct route using EC (cysteine—tRNA ligase) and the indirect pathway with EC (O-phosphoseryl-tRNA ligase) and EC [2].

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0043766
CAS Registry Number: 1239229-21-0
UniProtKB/Swiss-Prot: (26) [show] [UniProt]


  1. Fukunaga, R., Yokoyama, S.
    Structural insights into the second step of RNA-dependent cysteine biosynthesis in archaea: crystal structure of Sep-tRNA:Cys-tRNA synthase from Archaeoglobus fulgidus.
    J. Mol. Biol. 370: 128-141 (2007). [PMID: 17512006]
  2. Hauenstein, S. I., Perona, J. J.
    Redundant synthesis of cysteinyl-tRNACys in Methanosarcina mazei.
    J. Biol. Chem. 283: 22007-22017 (2008). [PMID: 18559341]
  3. Yuan, J., Palioura, S., Salazar, J. C., Su, D., O'Donoghue, P., Hohn, M. J., Cardoso, A. M., Whitman, W. B., Soll, D.
    RNA-dependent conversion of phosphoserine forms selenocysteine in eukaryotes and archaea.
    Proc. Natl. Acad. Sci. USA 103: 18923-18927 (2006). [PMID: 17142313]

[EC created 2009]