Regulation and activation of phytoene synthase, a key enzyme in carotenoid biosynthesis, during photomorphogenesis

• Published in: Planta Vol. 211; no. 6; pp. 846 - 854
• Main Authors: Beyer, P, Hugueney, H, Kleinig, H, Lintig, J. von
• Format: Journal Article
• Language: English
• Published: Berlin Springer-Verlag 01-11-2000; Springer
• Subjects: Agronomy. Soil science and plant productions; Alkyl and Aryl Transferases - genetics; Alkyl and Aryl Transferases - metabolism; biochemical pathways; Biological and medical sciences; Biosynthesis; Brassica - enzymology; Brassica - growth & development; Brassica - radiation effects; Carotenoids; Carotenoids - biosynthesis; chemical constituents of plants; chlorophyll; Chlorophylls; Chloroplasts; Chromoplasts; Economic plant physiology; Enzyme Activation; enzyme activity; Enzymes; etiolation; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Geranylgeranyl-Diphosphate Geranylgeranyltransferase; Growth and development; ligases; light; messenger RNA; Molecular Sequence Data; Morphogenesis; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; Physical agents; phytochrome; phytoene; plant development; Plant physiology and development; Plants; Plastids; RNA, Messenger - genetics; RNA, Messenger - metabolism; Seedlings; Sinapis alba; Thylakoids; Vegetative apparatus, growth and morphogenesis. Senescence; Chlorophyll; Enzyme; Environmental factor; Activation; Biosynthesis; Metabolic pathway; Synthase; Photomorphogenesis; Morphogenesis; Regulation(control); Enzymatic activity; Cruciferae; Photosynthetic pigment; Dicotyledones; Light; Angiospermae; Flavoring crop; Spermatophyta; Sinapis alba; Localization; Carotenoid; Chloroplast
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250000352

During photomorphogenesis in higher plants, a coordinated increase occurs in the chlorophyll and carotenoid contents. The carotenoid level is under phytochrome control, as reflected by the light regulation of the mRNA level of phytoene synthase (PSY), the first enzyme in the carotenoid biosynthetic pathway. We investigated PSY protein levels, enzymatic activity and topological localization during photomorphogenesis. The results revealed that PSY protein levels and enzymatic activity increase during de-etiolation and that the enzyme is localized at thylakoid membranes in mature chloroplasts. However, under certain light conditions (e.g., far-red light) the increases in PSY mRNA and protein levels are not accompanied by an increase in enzymatic activity. Under those conditions, PSY is localized in the prolamellar body fraction in a mostly enzymatically inactive form. Subsequent illumination of dark-grown and/or in far-red light grown seedlings with white light causes the decay of these structures and a topological relocalization of PSY to developing thylakoids which results in its enzymatic activation. This light-dependent mechanism of enzymatic activation of PSY in carotenoid biosynthesis shares common features with the regulation of the NADPH:protochlorophyllide oxidoreductase, the first light-regulated enzyme in chlorophyll biosynthesis. The mechanism of regulation described here may contribute to ensuring a spatially and temporally coordinated increase in both carotenoid and chlorophyll contents.