Sunflower (Helianthus annuus) plastidial lipoyl synthase genes and their impact on glycerolipid rearrangement in Arabidopsis

Autor: Martins-Noguerol, Raquel, Moreno-Pérez, Antonio Javier, Acket, Sebastien, Garcés Mancheño, Rafael, Troncoso-Ponce, M. Adrián, Salas, Joaquín J., Thomasset, Brigitte, Martínez-Force, Enrique
Rok vydání: 2019
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 2017-8344
Popis: 9th European Symposium on Plant Lipids 07 July 2019 - 10 July 2019, Marseille
Lipoyl synthases are key enzymes in lipoic acid biosynthesis, a cofactor of several enzyme complexes involved in central metabolism. Plant pyruvate dehydrogenase complex (PDH) is located in mitochondria and plastids, where it catalyses oxidative decarboxylation of pyruvate to produce acetyl-CoA, CO2 and NADH, the first step in fatty acids biosynthesis in these organelles. Among their different components, the E2 subunit of PDH is a dihydrolipoylated protein, which needs the lipoic acid prosthetic group to be active. De novo lipoic acid biosynthesis is performed from octanoyl-ACP by the successive action of the enzymes octanoyltransferase (LIP2) and lipoyl synthase (LIP1). In the present study, two plastidial lipoyl synthases genes from sun¿ower (Helianthus annuus) were identified (HaLip1p1 and HaLip1p2), sequenced and cloned in a heterologous production system (Escherichia coli). Gene expression studies revealed similar expression patterns for both isoforms with a slight predominance of HaLip1p1 in vegetative tissues and mature seeds. Tertiary structure models for both enzymes showed the same theoretical catalytic sites in both enzymes using lipoyl-lys and 5-deoxyadenosine as docking substrates. E. coli cells overexpressing HaLIP1p1 and HaLIP1p2 did not show large differences in fatty acids profile, but in vivo activities of both proteins were tested by complementation of a defective lipoyl synthase E. coli JW0623 mutant. Although significant differences were not detected in total fatty acids composition of Arabidopsis thaliana transgenic seeds overexpressing each of both proteins, a lipidomic analysis revealed a redistribution in glycerolipids species, with increased PE content and a decrease in DAGs, PC and TAGs containing unsaturated fatty acids. A depletion of SAM cofactor caused by HaLIP1p1 and HaLIP1p2 overexpression in transgenic plants could be the explanation for this remodelling by affecting phosphocholine synthesis. * This work was funded by the MINECO and FEDER Project AGL2017-83449-R and CSIC Project I-LINK1186.
Databáze: OpenAIRE
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