ALTERNATIVE PATHWAY FOR POLYUNSATURATED FATTY ACIDS (PUFAs) BIOSYNTHESIS IN TRYPANOSOMATIDS

TRIPODI K.; BUTTIGLIERO L.; PETRINI G. A.; ALTABE S. G.; UTTARO A. D.

Misiones

Congreso; XL Reunión de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2004

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Trypanosome brucei and Leishmania major are parasitic protozoa belonging to the trypanosomatid family, causative agents of human African sleeping sickness and leishmaniasis, respectively. They have a high proportion on long-chain PUFAs which appear to be generated by a different pathway than their mammalian host. This fact and the assumption that unsaturation degree of membrane lipids is crucial for parasite viability, make desaturases a good target for chemotherapeutic drugs. At present it is known that desaturation beyond some 18:2 substrates occurs throughout front end desaturases and may follow Euglena gracilis or mammalian pathway. Our main goal was to identify the route of PUFAs biosynthesis in trypanosomatids. We cloned and expressed 3 front end desaturases from L. major (delta 5, delta 6, and delta 8-desaturases) and one from T. brucei (delta 6-desaturase) managing available information in the genome project of each organism. After expression in yeast with the addition of different substrates, we purified the fatty acids and analysed their profile by GC-MS. Sequence analyses lead us to predict that delta 6 desaturases were actually delta 4 desaturases and this result was corroborated by activity studies. Previous work in our lab indicated that T. brucei contains a delta 12 desaturase, whereas no information is still available about the occurrence of a delta 15 desaturase. Altogether our results suggest that PUFAs biosynthesis in trypanosomatids follows the recently described E. gracilis pathway.