The identification of a sequence related to apicomplexan enolase from Sarcocystis neurona

Equine protozoal myeloencephalitis (EPM) is a neurological disease caused by Sarcocystis neurona, an apicomplexan parasite. S. neurona is also associated with EPM-like diseases in marine and small mammals. The mechanisms of transmission and ability to infect a wide host range remain obscure; therefore, characterization of essential proteins may provide evolutionary information allowing the development of novel chemotherapeutics that target non-mammalian biochemical pathways. In the current study, two-dimensional electrophoresis and matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectrometry were combined to characterize and identify an enolase protein from S. neurona based on peptide homology to the Toxoplasma gondii protein. Enolase is thought to be a vestigial, non-photosynthetic protein resulting from an evolutionary endosymbiosis event of an apicomplexan ancestor with green algae. Enolase has also been suggested to play a role in parasite stage conversion for T. gondii. Characterization of this protein in S. neurona and comparison to other protozoans indicate a biochemical similarity of S. neurona enolase to other tissue-cyst forming coccidians that cause encephalitis.