Micro Cryptosporidium Iron-related Protein Expression, Purification And Function

Cryptosporidium parvum (Category B agent) is a protozoan parasite that can cause severe watery diarrhea in humans and animals. Currently, only a single drug (i.e., nita-zoxanide [NTZ]) has been approved for treating cryptosporidiosis in immunocompe-tent (but not immunocompromized) patients in the United States. We have successfully expressed recombinant mitochondrial-type ferredoxin (mtFd) and ferredoxin:NADP+ reductase (mtFNR) from Cryptosporidium parvum and characterized their biochemical features for the first time. Both CpmtFd and CpmtFNR were obtained and purified as holo-proteins, in which the correct assembly of [2Fe-2S] cluster in Fd and that of FAD in FNR were confirmed and characterized by UV/Vis and EPR. These proteins were fully functional and CpmtFNR was capable of transferring electrons from NADPH to CpmtFd in a cytochrome c-coupled assay that followed a typical Michaelis-Menten ki-netics. Apicomplexan mtFd and mtFNR proteins were evolutionarily divergent from their counterparts in humans and animals, and could be explored to be acted as poten-tial drug targets in Cryptosporidium and other apicomplexans.