Department of Microbiology and Immunology
Gene Expression; Infectious Disease; Microbial Pathogenesis; Microbiology; Molecular and Cellular Biology; Molecular Basis of Disease; Protein Function and Structure; Regulation of metabolism; RNA; Transcription and Translation
Developmental Regulation of Gene Expression in Trypanosomes
Our laboratory uses molecular biological and biochemical approaches to study a group of parasitic protozoans that cause disease in humans and domestic animals in much of the tropical world. Two projects focus on Trypanosoma brucei, the causative agent of African sleeping sickness, which is transmitted by the tse-tse fly. Other projects focus on Trypanosoma cruzi, which causes Chagas disease in South and Central America and is transmitted by the reduviid bug. Treatment for these diseases is severely limited due to increasing drug resistance and issues of drug toxicity or lack of available drugs. The goal of our work is to discover and exploit regulatory events that occur in the parasite life cycle that may be used to prevent growth or transmission of the parasite.
The first project, examines a pair of unique RNA binding proteins, P34 and P37, which are highly homologous to one another. We have shown that these proteins interact with 5 S rRNA and ribosomal protein L5 in a unique pre-ribosomal complex that is essential for ribosomal biogenesis and survival of the trypanosomes. The role of these trypanosome-specific proteins in the normally highly conserved pathway of ribosomal biogenesis is a surprising finding and may suggest that these proteins and the pre-ribosomal complex could be developed as targets for chemotherapy. In addition, we have studied these proteins as models for mechanisms of developmental regulation in trypanosomes. We have developed a fluorescence resonance energy transfer assay that allows us to study the interactions within the pre-ribosomal complex and also allows us to develop a high throughput screen for small molecules that disrupt the complex in trypanosomes and do not harm the human host. We have also begun work characterizing this complex in the related parasite, T. cruzi.
The second project centers on the mitochondrial ATP synthase of T. brucei. This protein complex couples the energy generated by the electron transport chain to the synthesis of ATP. In T. brucei we have shown that the ATP synthase is regulated through the life cycle of the organism by several unique mechanisms which appear to be different from the regulatory mechanisms for other mitochondrial proteins such as those in the electron transport chain. This regulation may be critical to understanding how this parasite responds to change in the environment due to the two host organisms (in this case, the tsetse fly and the cow). We have shown that the ATP synthase is responsible for maintaining a mitochondrial membrane potential in the bloodstream stage of the parasite. This membrane potential is required for the parasite’s survival since without it the parasite cannot pre-adapt for survival in the insect vector. Recently we have shown that the F0 membrane component is comprised of three different c subunits, suggesting that this may provide an adaptive response under different environmental confditins. These results suggest that the ATP synthase may provide an excellent target for drug development focused on preventing transmission of the parasite by the insect.
In the third project in long standing collaboration with Dr. Beatriz Garat at the Universidad de la Républica in Uruguay, we are examining both DNA and RNA binding proteins which regulate gene expression in Trypanosoma cruzi.