Molecular characterization of ribonucleotide reductase from Cryptosporidium parvum

The Apicomplexan enteric parasite, Cryptosporidium, infects a broad range of mammals, birds, fish and reptiles. Cryptosporidium parvum, the principal causative agent of human cryptosporidiosis, has emerged as a major contributor to waterborne outbreaks of this disease. The absence of effective drugs against C. parvum has necessitated the search for new drug targets. One attractive class of target enzymes is ribonucleotide reductase, an essential enzyme required for the de novo synthesis of deoxyribonucleotides. We report the cloning and sequencing of the small and large subunits of ribonucleotide reductase from a C. parvum genotype 2 isolate, GCH1. Southern blot analysis showed that these subunits are encoded by single copy genes. Both subunits have been expressed as recombinant proteins in Escherichia coli.