MODIFICATION OF SPHINGOBASES IN TRYPANOSOMATIDS

VACCHINA, PAOLA; TRIPODI, KARINA; UTTARO, ANTONIO

San Miguel de Tucumán

Congreso; XLV Reunión anual de SAIB; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Sphingolipids (Spl) are important class of lipids and essential components of eukaryotic membranes. In addition to their structural role, they are involved in cellular processes such as growth regulation, apoptosis and stress response. Previously, we cloned a D4-Spl Des from Trypanosoma brucei and characterized it as a pure desaturase, in contrast to bifunctional desaturases/hydroxylases. In this work, we cloned the orthologous enzyme of T. cruzi in pYES2, and analyzed the enzymatic activity in a yeast mutant for long chain base (LCB) hydroxylase (sur2), being typified also as a desaturase. Since parasites are subjected to changes throughout their lives cycles, is possible that Spl are implicated. After the examination of the LCB content of parasite membranes, we found an important increase in the levels of unsaturated versus saturated 18 C LCB in bloodstream T. brucei, in comparison with procyclic form. This level is intermediate in epimastigotes of T. cruzi. These results may indicate some type of regulation of the D4-SplDes. Finally, we investigated the effect of GT11, a strong inhibitor of D4-SplDes activity, on different cultures of trypanosomas. Interestingly, whereas epimastigotes of T. cruzi remained growing albeit the activity of D4-SplDes droped to the 20% of untreated cultures, bloodstream form of T. brucei arrested their growth after 24 hs in presence of 10 uM GT11.