Student Abstract

Cryptosporidium phosphoenolpyruvate carboxylase as a molecular target for novel potent antiparasitic drugs

Rachael Y. Lahar, Shahbaz M. Khan, and William H. Witola

Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL

Cryptosporidium parvum is a zoonotic parasite that causes a diarrheal syndrome in neonatal and immunocompromised animals and humans worldwide. Currently, there is no fully effective drug nor vaccine against C. parvum. Moreover, parasite oocysts contaminate the environment and are resistant to most chemical disinfectants. Thus, it is urgent to identify strategies for developing efficacious drugs against C. parvum. The C. parvum genome lacks the tricarboxylic acid cycle and oxidative phosphorylation steps, suggesting that the parasite depends solely on glycolysis for metabolic energy. C. parvum glycolytic enzymes differ from mammalian orthologs, making them ideal targets for anti-cryptosporidial drug development. In previous work, our laboratory identified inhibitors for C. parvum glycolytic enzymes lactate dehydrogenase and pyruvate kinase that prevented parasite growth and disease in mice. The focus of the present study was another glycolytic enzyme, C. parvum phosphoenolpyruvate carboxylase (CpPEPc), which contributes to synthesis of pyruvate that is utilized for generation of metabolic energy. We will develop and validate an in vitro coupled-enzymatic assay involving the sequential catalytic activities of CpPEPc and C. parvum malate dehydrogenase, leading to the synthesis of pyruvate. The assay will be used to screen compound libraries for inhibitors of CpPEPc that will then be analyzed for anti-cryptosporidial activity both in vitro and in vivo. Ultimately, our goal is to unveil validated lead compounds for developing new effective drugs for treating C. parvum infection.

Research Grant: Bill and Melinda Gates Foundation (completed), USDA (pending)

Student Support: Office of the Director, NIH, T35 OD011145