Structural insights into the second step of RNA-dependent cysteine biosynthesis in archaea: crystal structure of Sep-tRNA:Cys-tRNA synthase from Archaeoglobus fulgidus.
Transferases;
Transferring alkyl or aryl groups, other than methyl groups;
Transferring alkyl or aryl groups, other than methyl groups (only sub-subclass identified to date)
In organisms like Archaeoglobus fulgidus lacking EC 6.1.1.16 (cysteine---tRNA ligase) for the direct Cys-tRNACys formation, Cys-tRNACys is produced by an indirect pathway, in which EC 6.1.1.27 (O-phosphoseryl-tRNA ligase) ligates O-phosphoserine to tRNACys, and EC 2.5.1.73 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 6.1.1.16 (cysteine---tRNA ligase) and the indirect pathway with EC 6.1.1.27 (O-phosphoseryl-tRNA ligase) and EC 2.5.1.73 [2].
Structural insights into the second step of RNA-dependent cysteine biosynthesis in archaea: crystal structure of Sep-tRNA:Cys-tRNA synthase from Archaeoglobus fulgidus.
Enzymatic reactions [BR:br08201]
2. Transferase reactions
2.5 Transferring alkyl or aryl groups, other than methyl groups
2.5.1 Transferring alkyl or aryl groups, other than methyl groups (only sub-subclass identified to date)
2.5.1.73
R08577 O-Phosphoseryl-tRNA(Cys) + Hydrogen sulfide <=> L-Cysteinyl-tRNA(Cys) + Orthophosphate
