Cyst(e)ine C-S lyase (C-DES), isolated from Synechocystis sp. PCC 6714, is a pyridoxal 5'-phosphate (PLP)-dependent enzyme. It catalyses the conversion of cystine to cysteine persulfide, pyruvate and ammonia. The enzyme can also use cysteine, but to a lesser extent. C-DES is an important enzyme in sulfur mobilisation and Fe-S cluster assembly and directs FeS cluster insertion into Synechocystis apoferridoxin in vivo.
The observation of a persulfidic intermediate mimics the NifS PLP dependent L-Cysteine desulphurase, although C-DES is missing the largely conserved active site cysteine associated with NifS enzymes. The mechanism for C-DES persulphide formation offers an alternative pathway for the formation of S(0), although the mode of transport of the elemental sulfur has yet to be determined.
Defined by 6 residues: HIS:A-111 [auth A-114]ASP:A-194 [auth A-197]ALA:A-196 [auth A-199]GLN:A-197 [auth A-200]LYS:A-220 [auth A-223]ARG:A-357 [auth A-360]