title: Tocopherol Cyclases-Substrate Specificity and Phylogenetic Relations.
abstract: 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.
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Dłużewska
authors.affiliation: Department of Medical Physics and Biophysics, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, Reymonta 19, 30-059, Kraków, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Szymańska
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Gabruk
authors.affiliation: Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary.|Department of Biotechnology, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Kós
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
authors.forename: Beatrycze
authors.initials: B
authors.lastname: Nowicka
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kruk
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002839:Chromans / Q000378:metabolism; D019751:Intramolecular Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D013379:Substrate Specificity; D020524:Thylakoids / Q000378:metabolism; D024505:Tocopherols / Q000378:metabolism; D014810:Vitamin E / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D002839:Chromans; D014810:Vitamin E; C013649:plastochromanol 8; D019751:Intramolecular Transferases; C103397:tocopherol cyclase; D024505:Tocopherols