Lipoic acid biosynthesis in Caenorhabditis elegans

MANSILLA MC; LAVATELLI, A; DE MENDOZA, D

Madison

Encuentro; 2018 Meeting in C. elegans Stress, Pathogenesis, Aging, Metablism and small RNAs; 2018

Universidad de Wisconsin

Lipoicacid (LA) is a universally distributed sulfur containing cofactor. It isessential for the functioning of multienzymatic complexes involved in oxidativeand one-carbon metabolism, and a potent antioxidant. Herewe show that Caenorhabditis elegans isable to synthesize LA and thus, this nematode could be a valuable model tostudy the metabolism of this coenzyme in multicellular organisms. By in silico analyses we found two nematodeproteins with considerable identity percentages with bacterial, human and yeastenzymes involved in lipoylation. M01F1.3 has homology with lipoate synthases,while ZC410.7 has sequence similarity with octanoyltransferases. In both cases RNAinterference (RNAi) experiments performed in N2 strain resulted in larval arrest and lower resistance to oxidative stresscompared to control animals. It was confirmed byWestern blot analyses that these treated worms had reduced protein lipoylationlevels. The arrested phenotype could not be rescued by the addition ofexogenous LA, whichlead us to think that synthesis of LA is essential in the worm. Besides, complementationassays with M01F1.3 rescue a Bacillussubtilis lipoate synthase mutant. In the other hand, expression of ZC410.7 functionallycomplement a yeast lip2 mutant,deficient in octanoyltransferase activity. Taken together, these resultsdemonstrate that M01F1.3and ZC410.7 are the C.elegans lipoate synthase and octanoiltransferase, respectively, and thatlipoate synthesis isessential for thecorrect development of the worms. Human patients with defects in protein lipoylationsuffer from severe neurological disorders and they receive treatments just toalleviate symptoms.Elucidation of how proteins become lipoylated in the nematode C. elegans would contribute to the understanding of the process inhumans and the development of new therapies.