Molecular Mechanism of Involved in Targeting and Import of Proteins into Glycosomes
Research in my laboratory focuses on the study of the molecular mechanisms involved in the assembly of a microbody organelle called a glycosome, which is found in protozoan parasites of the order Kinetoplastida.
The glycosome compartmentalizes a battery of metabolic enzymes essential for glycolysis, b-fatty acid oxidation, purine salvage, and pyrimidine and ether-lipid biosynthetic pathways. My laboratory is investigating the molecular machinery involved in the biogenesis of this glycosome, with a particular focus to understanding the mechanisms involved in targeting and translocation of nascent polypeptides, synthesized in the cytosol, across the glycosomal lipid bilayer membrane.
To study these biological processes, we are using the medically important protozoan parasites Leishmania donovani and Trypanosoma cruzi as model systems. Recently, we have cloned the genes for LdPEX5 and LdPEX14, two proteins that are required for glycosome assembly. LdPEX5 is a cytosolic protein that specifically recognizes and binds a carboxy terminal tripeptide signal, present on most glycosomal proteins, and tags these proteins for import into the glycosome. LdPEX14 is a glycosomal integral membrane that has been demonstrated, in vitro, to tightly associate with LdPEX5.
This LdPEX5-LdPEX14 interaction has been conjectured to be an essential step for the translocation of proteins across the glycosomal membrane. Currently, we are employing a multidisciplinary approach using molecular biology, genetic, immunocytochemistry, and protein chemistry techniques to structurally characterize LdPEX5 and LdPEX14 interaction and to dissect the role of these proteins in the glycosome biogenesis.
Moreover, the rapidly growing Leishmania and Trypanosome genome databases have facilitated the employment of a functional genomics/proteomics strategy using LdPEX5 and LdPEX14 as bait molecules to further elucidate and characterize the glycosome biogenesis machinery. It is postulated that since the glycosome houses a multiplicity of key metabolic enzymes crucial for parasite viability, the glycosome biogenesis machinery represents an attractive target for development of novel leishmaniacidal and trypanocidal chemotherapeutics agents.
- Canada Research Chair in Immunoparasitology