Effect of sunflower (Helianthus annuus L.) lipoic acid metabolism in plastidial fatty acids biosynthesis
| Autor: | Martins-Noguerol, Raquel, Moreno-Pérez, Antonio Javier, Acket, Sebastien, Garcés Mancheño, Rafael, Salas, Joaquín J., Troncoso-Ponce, M. Adrián, Thomasset, Brigitte, Martínez-Force, Enrique |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 2017-8344 |
| Popis: | 17th Euro Fed Lipid Congress 20-23 October 2019, Seville, Spain Plastids are the major site of de novo fatty acid synthesis in plants, where acetyl-CoA is the first intermediate. This metabolite is generated from pyruvate through the action of the plastidial pyruvate dehydrogenase complex (PDH), which catalyses the oxidative decarboxylation of pyruvate to produce acetyl-CoA, CO2 and NADH. E2 subunit of PDH is a dihydrolipoyl acetyltransferase which needs lipoic acid prosthetic group bound covalently for the correct function of the full complex. Lipoic acid is a sulfur containing coenzyme which proceeds from the short-chain fatty acid octanoate with two thiol substituents at C6 and C8. In plants, very little is known about lipoic acid biosynthesis but octanoyltransferase (LIP2) and lipoyl synthase (LIP1) enzymes have been proposed to be involved in de novo synthesis and attachment of this cofactor to their specific targets. In the first step, LIP2 transfer the octanoyl moiety from octanoyl-acyl carrier protein (ACP) to apoproteins such as E2-PDH. Then LIP1 activity generates in lipoic acid by addition of two sulfur atoms to produce the lipoic acid and thus the lipoylated protein. Since no transport of lipoic acid has been demonstrated into plastids, these organelles need specific plastidial LIP1 and LIP2 activities. An essential LIP1 and two redundant LIP2 enzymes have been elucidated in chloroplasts from A. thaliana. Here, we report two LIP2 isoforms being expressed in sunflower plastids. Both genes were identified (HaLIP2p1 and HaLIP2p2) and cloned in a heterologous system (Escherichia coli). Effect of both HaLIP2p1 and HaLIP2p2 in fatty acid biosynthesis in bacteria was analyzed. Molecular characterization of protein sequences and tertiary structure models for both novel octanoyltransferases were made and critical residues in active site were studied to understand activity mechanism of both proteins. Transgenic A. thaliana plants overexpressing HaLIP2p1 were generated and total fatty acids from transgenic matured seeds were measured. To detect possible changes in lipid metabolism of this overexpression, a lipidomic approach of transgenic seeds was also performed. * This work was funded by the MINECO and FEDER Project AGL2017-83449-R and CSIC Project I-LINK1186. |
| Databáze: | OpenAIRE |
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