Tocopherol Cyclases-Substrate Specificity and Phylogenetic Relations

• Published in: PloS one 2016-07, Vol.11 (7), p.e0159629-e0159629
• Main Authors: Dłużewska, Jolanta, Szymańska, Renata, Gabruk, Michal, Kós, Peter B, Nowicka, Beatrycze, Kruk, Jerzy
• Format: Article
• Language: English
• Subjects: Acids; Anabaena variabilis; Analysis; Antioxidants; Arabidopsis; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Bacteria; Biochemistry; Bioinformatics; Biology and Life Sciences; Biophysics; Biosynthesis; Biotechnology; Catalysis; Catalytic activity; Chemical synthesis; Chlamydomonas reinhardtii; Chloroplasts; Chromans - metabolism; E coli; Enzymatic activity; Enzyme activity; Enzyme kinetics; Intramolecular Transferases - chemistry; Intramolecular Transferases - genetics; Intramolecular Transferases - metabolism; Ligases; Lipids; Localization; Micelles; Photosynthesis; Phylogenetics; Phylogeny; Physical sciences; Physiological aspects; Physiology; Plasmids; Proteins; Research and Analysis Methods; Substrate Specificity; Substrates; Synechocystis; Thylakoids; Thylakoids - metabolism; Tocopherol; Tocopherols; Tocopherols - metabolism; Vitamin E; Vitamin E - analogs & derivatives; Vitamin E - metabolism
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0159629

In the present studies, we focused on substrate specificity of tocopherol cyclase, the key enzyme in the biosynthesis of the tocopherols and plastochromanol-8, the main plant lipid antioxidants, with special emphasis on the preference for tocopherols and plastochromanol-8 precursors, taking advantage of the recombinant enzyme originating from Arabidopsis thaliana and isolated plastoglobules, thylakoids and various model systems like micelles and thylakoids. Plastoglobules and triacylglycerol micelles were the most efficient reaction environment for the cyclase. In various investigated systems, synthesis of γ-tocopherol proceeded considerably faster than that of plastochromanol-8, probably mainly due to different localization of the corresponding substrates in the analyzed lipid structures. Moreover, our study was complemented by bioinformatics analysis of the phylogenetic relations of the cyclases and sequence motifs, crucial for the enzyme activity, were proposed. The analysis revealed also a group of tocopherol cyclase-like proteins in a number of heterotrophic bacterial species, with a conserved region common with photosynthetic organisms, that might be engaged in the catalytic activity of both groups of organisms.