Authors

A J Mbekeani¹; W Stanley¹; M Meissner²; E Pohl¹; P Denny¹;  ¹ University of Durham;  ² University of Glasgow

Discussion

The metabolism of fatty acids and cholesterol is essential to all eukaryotic organisms and occurs in various organelles, including peroxisomes. Other than lipid metabolism, peroxisomes contain many enzymes involved in different metabolic processes. One key enzyme found in most peroxisomes is catalase. Catalase neutralizes hydrogen peroxide, preventing toxic build up within cells. This enzyme has overtime become an identifier of peroxisomes in many organisms. However, this is controversial in Toxoplasma gondii. The use of catalase as a marker for peroxisomes in this apicomplexan parasite has been disputed, and in some cases lead to the belief that the T. gondii does not maintain these organelles. In this project we are taking a different approach to answer this question of T. gondii peroxisomes.
Through evolution T. gondii has maintained, within its genome, many of the genes encoding peroxisomal proteins, called peroxins (PEX). Here we investigate the presence of peroxisomes within T. gondii using PEX. The experimental approach looks at characterization of TgPEX5 and TgPEX7 proteins and their associated ligands TgSCP2 and TgThiolase respectively. TgSCP2 with a C-terminal (PTS1), binds TgPEX5, whilst TgThiolase with an N-terminal PTS2, binds TgPEX7. Using reverse genetics and proteomics within the in vitro stages of this parasite, we aim to show the presence of peroxisomes in T. gondii.