IMPORTIM-LIKE PROTEINS INVOLVED IN NUCLEAR TRANSPORT ARE ESSENTIAL IN TRYPANOSOMA BRUCEI

MEYER, CHRISTIAN; FASSOLARI, MATÍAS; TORRES, HÉCTOR; FLAWIÁ, MIRTHA M; ALONSO, GUILLERMO D.

Puerto Madryn-Argentina

Congreso; XLVI Reunión Anual de SAIB; 2010

Trypanosomatids are protozoan parasites with a complex life cycle that alternate between hosts and differentiation stages. Therefore, they are subjected to environmental changes that must necessarily be compensated by a capable regulatory mechanism. The nuclear envelope provides a physical separation between the nucleus and the cytoplasm allowing precise control of many cellular processes through the selective regulation of transport between the two compartments. While small proteins can pass through the nuclear pore complex (NPC) in a passive way, those of larger size require a nuclear localization signal and specific transporters engaged in active transport across the NPC. We previously reported the finding and cloning of two genes with sequence identity to the karyopherins, importin alpha and importin beta, two well-characterized transporters in other species but with unknown function in trypanosomatids. Here we show, by RNAi, that both importins are essentials in T. brucei procyclic forms. We also generated fusions to fluorescent proteins and were able to study the localization dynamics of these inportins. Since orthologous proteins have been crystallized, it was possible to model the three-dimensional structure of the proposed importins in trypanosomatids. So far our experimental data is consistent with the suggested cellular function. Keywords: karyopherins, Trypanosomatids, RNA interference