Characterization of P. falciparum apyrase and analysis of the role of Ca2+ in T. gondii egress.

Author(s)

Lucas Borges Pereira

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2016-02-18

Examining board members

Celia Regina da Silva Garcia; Alexandre Bruni Cardoso; Deborah Schechtman; Irene da Silva Soares; Gerhard Wunderlich

• Advisor: Celia Regina da Silva Garcia

Abstract

Plasmodium falciparum and Toxoplasma gondii are protozoan parasites that belong to phylum Apicomplexa. Apirases are metabolizing enzymes of extracellular nucleotides. In this work we show for the first time the presence of an apyrase in P. falciparum, which was able to degrade extracellular ATP. RTqPCR analysis revealed the expression of apyrase throughout the intraerythrocytic cycle. Addition of apyrase inhibitors was able to impair the development of the parasites and the invasion of new erythrocytes by merozoites, thus suggesting a role of apyrase in these processes. Calcium signaling is universal and vital to all cells. To better understand the cellular physiology of P. falciparum we construct a new strain of transgenic parasites, PfGCaMP3, which enable us to monitor the Ca2+ dynamics without using invasive protocols. Similarly we use a new strain of T. gondii that stably express the Ca2+ indicator GCaMP3 to study the role Ca2+ in parasite egress. T. gondii has the Ca2+ required to promote this process, however extracellular Ca2+ acts as an enhancer factor in this crucial step of the lytic cycle. (AU)

• FAPESP's process: 10/51593-3 - Heterologous expression and biochemical characterization of apyrase from the parasite Plasmodium falciparum
• Grantee: Lucas Borges Pereira
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)