The University of Georgia College of Veterinary Medicine

eorgia Veterinary Scholars Program

GVSP Summer 2008 Scholars

Georgia Veterinary Scholar	Faculty Mentor

Laura Reiss University of Georgia Class of 2011	Dr. Roberto Docampo

Characterization of Acidocalcisomal Proteins in Trypanasoma brucei and Trypanasoma cruzi

Reiss, Laura*. Ulrich, Paul; Docampo, Roberto; College of Veterinary Medicine, University of Georgia, Athens, GA; Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA

The acidocalcisome is a dense, acidic organelle containing high concentrations of phosphorus present as pyrophosphate (PPi) and polyphosphate (Poly P) complexed with calcium and other cations. The acidocalcisome evolved before bacterial and eukaryotic lineages diverged, has been conserved during
evolution in both bacteria and humans, and was originally described in the pathogens Trypanosoma brucei and T. cruzi. The physiological functions of the acidocalcisome include cation storage, phosphate metabolism,intracellular pH homeostasis, and osmoregulation. Our goal is to investigate the role of acidocalcisome proteins by using T. brucei and T. cruzi as models. Proteomic analysis of trypanasomatid acidocalcisomes suggests the presence of syntaxin, a targeting protein, and vacuolar transporter chaperones (VTC’s), proteins
implicated in membrane-related processes such as protein trafficking, endocytosis, vacuole fusion, and poly P homeostasis. Only VTC1 has been characterized in T. brucei. TbVTC4, as well as homologues present in T.
cruzi genome (TcVTC1, TcVTC4), may have similar functions. Knockdown of TbVTC4 expression by RNAi inhibited growth and reduced short chain poly P levels by ~3-fold. To confirm the localization of VTC’s in the acidocalcisome, we designed GFP fusion constructs for overexpression in T. cruzi and transfections are
under drug selection. Additionally, we are also investigating the function and localization of syntaxin in T. brucei by RNAi and by overexpression of the protein fused with GFP, respectively. The syntaxin RNAi experiments are undergoing, and the syntaxin overexpression transfectants are under drug selection.

Research Support: NIH, Docampo Laboratory, UGA
Student Support: NIH 1 T35 RR022685-01A1 Grant to the University of Georgia