The Role of Carbonic Anhydrase in Social Motility of Trypanosoma brucei
Authors:Walter Hardesty, Walter Hardesty, Edwin Saada
Mentor:Kent Hill, Principal Investigator, UCLA
Trypanosoma brucei is a protozoan parasite that causes African sleeping sickness, a disease of high mortality rates in sub-Saharan Africa. T. brucei has a complex lifecycle that alternates between a tsetse fly vector and a mammalian host. In the insect vector, migration through several tissues is required for maturation into mammalian-infectious forms. Despite the prevalence of surface interaction throughout the T. brucei lifecycle, little is known about how surface contact impacts parasite behavior because African trypanosomes have been traditionally studied in suspension culture. The insect form of T. brucei engages in social motility (SoMo) when cultivated on semisolid agarose surfaces. It was previously found that SoMo is affected by changes in CO2 levels and regulated by flagellar adenylate cyclases (ACs), which catalyze the synthesis of cAMP. In many organisms, ACs function as CO2 sensors, and in this capacity, rely on carbonic anhydrases (CA), which are enzymes that interconvert CO2 and bicarbonate. T. brucei has a single carbonic anhydrase, which is putatively located in the flagellum. Here the role of the T. brucei CA as a mediator of cAMP signaling and social motility is investigated specifically. To test this hypothesis, a knockdown of CA was first generated using tetracycline-inducible RNA interference. SoMo was then tested at different CO2 concentrations. Cumulative growth data collected on clonal knockdown (KD) lines during un-induced and induced conditions revealed that CA was does not produce a growth defect in suspension culture. Data from quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) demonstrated depletion of CA expression upon RNAi induction. SoMo assays are in progress to assess KD impact on social motility. These studies provide insight into the role of CA as an early step in SoMo and suggest CA may control cAMP signaling, thereby providing a novel target for therapeutic agents.