Nematode M01F1.3 and C45G3.3 functionally complement microbial mutants in lipoylation pathways

MANSILLA, MC; DE MENDOZA, D; LAVATELLI, A

Córdoba

Congreso; LII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2016

SAIB

Lipoic acid (LA)is a covalently bound sulfur-containing cofactor present in multienzymescomplexes involved in oxidative and one-carbon metabolism. The ways in whichproteins become lipoylated are very well characterized in prokaryotes, whileinformation concerning eukaryotes is scarce. Human patients with defectivelipoylation pathways receive treatment just to alleviate symptoms. For this reason,we have started the study of LA metabolism in the model organism Caenorhabditis elegans. We havepreviously demonstrated that the worm is capable of synthesizing LA and thatthe enzyme M01F1.3 was involved in the process, as blocking its expressioncaused a reduction in protein lipoylation levels. In order to confirm its role,we expressed the worm protein in bacterial strains defective in different stepsof lipoylation pathways. M01F1.3 was only able to rescue growth of Bacillus subtilis and Escherichia coli lipoate synthase (lipA) mutants. Another possible enzymeinvolved in nematode protein lipoylation is C45G3.3, which has considerableidentity of primary sequence with bacterial lipoate ligases. The worm proteinwas effective to complement a Saccharomycescerevisiae lip3 mutant. We also foundthat when expressing C45G3.3 in a B.subtilis strain deficient in lipoate ligase (lplJ), it recovered its ability to grow in a minimal medium whensupplemented with octanoate but not with LA.