Current state of carotenoid biosynthesis in chloroplasts of eucaryotes

The author discusses the current state of biochemical and genetic aspects of carotenoid biosynthesis in chloroplasts of algae and higher plants. Two ways of biosynthesis of key C5-isoperene units have been considered: 1) from acetate (C2) via mevalonic acid (C6) and its enzymatic conversions up to isopenthenyl diphosphate (C5) and 2) from glucose (C6) to formation of glyceraldehyde-3-phosphate (C3), to piruvate and their condensation via intermediate products up to isopenthenyl diphosphate (C5). Further biosynthesis of carotenoids from isopenthenyl diphosphate (C5) and dimethylallyl diphosphate (C5) in every organism is effected by the common scheme with further conservation of them up to geranyl diphosphate (C10), farnesyl diphosphate (C15), geranylgeranyl diphosphate (C20) and synthesis of phytoene (C40). All stages of phytoene desaturation up to formation of acyclic compounds are discussed. It is shown how in the process of subsequent oxidation and formation of hydroxy-, epoxy- and oxo-groups cyclic xanthophylls in chloroplasts of plants and algae are formed. Genetic control over biosynthesis of carotenoids is discussed.