Trypanosoma brucei centrin5 is enriched in the flagellum and interacts with other centrins in a calcium-dependent manner.

Centrin is an evolutionarily conserved EF-hand-containing protein, which is present in eukaryotic organisms as diverse as algae, yeast, and humans. Centrins are associated with the microtubule-organizing center and with centrosome-related structures, such as basal bodies in flagellar and ciliated cells, and the spindle pole body in yeast. Five centrin genes have been identified in Trypanosoma brucei (T. brucei), a protozoan parasite that causes sleeping sickness in humans and nagana in cattle in sub-Saharan Africa. In the present study, we identified that centrin5 of T. brucei (TbCentrin5) is localized throughout the cytosol and nucleus and enriched in the flagellum. We further identified that TbCentrin5 binds Ca2+ ions with a high affinity and constructed a model of TbCentrin5 bound by Ca2+ ions. Meanwhile, we observed that TbCentrin5 interacts with TbCentrin1, TbCentrin3, and TbCentrin4 and that the interactions are Ca2+ -dependent, suggesting that TbCentrin5 is able to form different complexes with other TbCentrins to participate in relevant cellular processes. Our study provides a foundation for better understanding of the biological roles of TbCentrin5.