Effects of sulphate-deficiency on cysteine metabolism in the green alga Chlorella sorokiniana

Plants, bacteria and fungi have the ability to assimilate inorganic sulphur and incorporate it into inorganic compounds. Animals on the contrary, do not assimilate inorganic sulphur; they require methionine as an essential amino acid for their source of sulphur nutrient. The amino acid cysteine (Cys) is the first committed molecule in plant metabolism containing sulphur and it is the sulphide donor for the generation of methionine, glutathione (GSH), phytochelatins, iron-sulphur clusters, vitamins, cofactors, and multiple secondary metabolites; that’s why the regulation of Cys-biosynthesis is critically important. The aim of this research was to investigate the effects of sulphur-deficiency on plant cysteine metabolism and to characterize the O-acetylserine(thiol)lyase (OASTL), a key-enzyme in cysteine biosynthesis.