Authors

Discussion

Trypanosomatids have been shown to possess an exclusive and finely regulated biosynthetic pathway for de novo synthesis of fatty acids (FAs) and particularly of polyunsaturated fatty acids (PUFAs).¹ This aspect justifies the high percentage of PUFAs that have been found in the lipid membranes of Trypanosoma brucei.² The key enzymes for the process of unsaturation are known as desaturases. The reaction catalysed by this class of enzyme is the insertion of a double bond in a stereospecific and regioselective manner on to the acyl carbon chain of a FA molecule.³ Thus, the hypothetical catalytic activity of Δ6-desaturase in the native organism T. brucei has been investigated. This study aims to confirm the substrate specificity and the activity of the Δ6-desaturases via genetic manipulation to tune its expression level in both procyclic (PCF) and bloodstream (BSF) forms of the native organism T. brucei.  We observed a specific variation in the PUFAs and lipids metabolism, which gave an insight on the biocatalytic function and essentiality of the enzyme. Particularly we were able to show an increase or decrease of docosahexaenoic acid (22:6) in BSF and docosapentaenoic acid (22:5) in PCF, accordingly whether Δ6-desaturases gene is overexpressed or knocked-down. Interestingly, we were able to observe via lipidomic analysis an increase in inositol phosphorylceramide (IPC) production, as a result of adaptation to different Δ6-desaturases expression levels and fat source content in the media, both in PCF and, surprisingly, in BSF.  Thus, we are currently further investigating the potential consequent effect on other proteins expression and any life-stage modifications, in which Δ6-desaturases might be involved.

References

1. Lee, S. H.; Stephens, J. L.; Englund, P. T., Nat Rev Microbiol, 2007, 5 (4), 287–297

2. Smith, T. K.; Bütikofer, P., Molecular and Biochemical Parasitology 2010, 172 (2), 66–79.

3. Tripodi, K. E. J.; Buttigliero, L. V.; Altabe, S. G.; Uttaro, A. D., FEBS Journal 2006, 273 (2), 271–280  

Acknowledgments

I would like to thank EPSRC CDT CRITICAT for founding.