An Oil Hyper-Accumulator Mutant Highlights Peroxisomal ATP Import as a Regulatory Step for Fatty Acid Metabolism in Aurantiochytrium limacinum

Etienne Deragon (1) , Martin Schuler (1) , Riccardo Aiese Cigliano (2) , Younes Dellero (3, 1) , Gregory Si Larbi (1) , D. Falconet (1) , Juliette Jouhet (1) , Eric Marechal (1) , Morgane Michaud (1) , Alberto Amato (1) , Fabrice Rébeillé (1)

1 LIPID
2 Sequentia Biotech SL
3 IGEPP - Institut de Génétique, Environnement et Protection des Plantes

Thraustochytrids are marine protists that naturally accumulate triacylglycerol with long chains of polyunsaturated fatty acids, such as ω3-docosahexaenoic acid (DHA). They represent a sustainable response to the increasing demand for these "essential" fatty acids (FAs). Following an attempt to transform a strain of Aurantiochytrium limacinum, we serendipitously isolated a clone that did not incorporate any recombinant DNA but contained two to three times more DHA than the original strain. Metabolic analyses indicated a deficit in FA catabolism. However, whole transcriptome analysis did not show down-regulation of genes involved in FA catabolism. Genome sequencing revealed extensive DNA deletion in one allele encoding a putative peroxisomal adenylate transporter. Phylogenetic analyses and yeast complementation experiments confirmed the gene as a peroxisomal adenylate nucleotide transporter (AlANT1), homologous to yeast ScANT1 and plant peroxisomal adenylate nucleotide carrier AtPNC genes. In yeast and plants, a deletion of the peroxisomal adenylate transporter inhibits FA breakdown and induces FA accumulation, a phenotype similar to that described here. In response to this metabolic event, several compensatory mechanisms were observed. In particular, genes involved in FA biosynthesis were upregulated, also contributing to the high FA accumulation. These results support AlANT1 as a promising target for enhancing DHA production in Thraustochytrids.

Mots clés: lipid metabolism; peroxisomal adenylate transporter; thraustochytrids; triacylglycerol (TAG); β-oxidation; ω3-docosahexaenoic acid (DHA)

Domaines: Sciences de l'environnement; Biochimie, Biologie Moléculaire

Etienne Deragon, Martin Schuler, Riccardo Aiese Cigliano, Younes Dellero, Gregory Si Larbi, et al.. An Oil Hyper-Accumulator Mutant Highlights Peroxisomal ATP Import as a Regulatory Step for Fatty Acid Metabolism in Aurantiochytrium limacinum. Cells, 2021, 10 (10), ⟨10.3390/cells10102680⟩. ⟨hal-03423342⟩