The unusual architecture and predicted function of the mitochondrion organelle in Cryptosporidium parvum and hominis species: the strong paradigm of the structure-function relationship

Abstract

Cryptosporidium spp. is a protozoan parasite that causes widespread diarrhoeal disease in humans and other animals and is responsible for large waterborne outbreaks of cryptosporidiosis. Unlike many organisms belonging to the phylum Apicomplexa, such as Plasmodium spp. and Toxoplasma gondii, there is no clinically proven drug treatment against this parasite. Some aspects of the basic biology of Cryptosporidium spp. such as the understanding of key metabolic pathways or the full description of the organellar compartment are still lacking. Here I present evidence of the anomalous shape and substructure of the mitochondrion organelle in C. parvum and C. hominis, which is closer to the Guillardia theta nucleomorph structure rather than to the canonical mitochondrion of the proximate apicomplexan T gondii. The atypical architecture is accomplished by an altered organellar metabolone, inferred by in silico conceptual prediction and characterized by unusual, partial and/or reduced pathways. However, phylogeneticanalyses of the mitochondrion and mitochondrion-related loci hsp60, hsp70 (dnaK), alternative oxidase (AOX) and superoxide dismutase (SOD) in C. parvum show diversiform evolutionary pathways, suggesting a "chimera" derived organelle. Taken together these data depict peculiar and intriguing aspects of the C. parvum and C. hominis anomalous mitochondrion framework for further comparative analysis of the organelle within the Cryptosporidium spp. order.