EC Number   |
Natural Substrates |
|---|
   2.5.1.73 | more |
two-step Cys-tRNACys formation: in organisms like Archaeoglobus fulgidus lacking a canonical cysteinyl-tRNA synthetase for the direct Cys-tRNACys formation, Cys-tRNACys is produced by the indirect pathway, in which the non-canonical O-phosphoseryl-tRNA synthetase, SepRS, ligates the non-canonical amino acid O-phosphoserine, Sep, to tRNACys, and the Sep-tRNA:Cys-tRNA synthase converts the produced Sep-tRNACys to Cys-tRNACys, overview, the SepRS/SepCysS pathway is the sole route for cysteine biosynthesis in the organism |
| 2.5.1.73 | O-phospho-L-seryl-tRNACys + sulfate |
evolutionary history of Cys-tRNACys formation, overview |
| 2.5.1.73 | O-phospho-L-seryl-tRNACys + sulfate |
the in vivo sulfur donor is not determined |
| 2.5.1.73 | O-phospho-L-seryl-tRNACys + sulfide |
the natural sulfur donor is not characterized, the activity of SepCysS provides a means by which both cysteine and selenocysteine can be added to the genetic code, the enzyme is responsible for Cys-tRNACys synthesis together with the O-phosphoseryl-tRNA synthetase in the organism containing a dispensable cysteinyl-tRNACys synthase, EC 6.1.1.16, overview |
| 2.5.1.73 | O-phospho-L-seryl-tRNACys + sulfide |
the natural sulfur donor is not characterized, the activity of SepCysS provides a means by which both cysteine and selenocysteine can be added to the genetic code, the enzyme is responsible for Cys-tRNACys synthesis together with the O-phosphoseryl-tRNA synthetase in the organism lacking the cysteinyl-tRNACys synthase, EC 6.1.1.16, overview |
| 2.5.1.73 | O-phospho-L-seryl-tRNACys + sulfide |
Methanocaldococcus jannaschii synthesizes Cys-tRNACys by an indirect pathway, whereby O-phosphoseryltRNA synthetase (SepRS) acylates tRNACys with phosphoserine (Sep), and Sep-tRNACys-tRNA synthase (SepCysS) converts the tRNA-bound phosphoserine to cysteine |
| 2.5.1.73 | O-phospho-L-seryl-tRNACys + sulfide |
the sulfur donor for this enzyme is unknown though in vitro sulfide is sufficient. Methanococcus maripaludis encodes both the direct and indirect paths for Cys-tRNACys synthesis. While sepS (encoding SepRS) can be deleted when the organism is grown in the presence of Cys, pscS (encoding SepCysS) cannot. SepCysS may possess an additional function in Methanococcus maripaludis that is essential |
