Systems-Based Analysis of the Sarcocystis neurona Genome Identifies Pathways That Contribute to a Heteroxenous Life Cycle

Blazejewski, Tomasz; Nursimulu, Nirvana; Pszenny, Viviana; Dangoudoubiyam, Sriveny; Namasivayam, Sivaranjani; Chiasson, Melissa A.; Chessman, Kyle; Tonkin, Michelle; Swapna, Lakshmipuram S.; Hung, Stacy S.; Bridgers, Joshua; Ricklefs, Stacy M.; Boulanger, Martin J.; Dubey, Jitender P.; Porcella, Stephen F.; Kissinger, Jessica C.; Howe, Daniel K.; Grigg, Michael E.; Parkinson, John

Finally, regulation of energy production has likewise evolved as a strategy for parasites to extend their host range, by tuning growth in relation to the host burden or carrying capacity (8) . We found only a limited number of differences between the enzyme complements of T. gondii and S. neurona. Notably, S. neurona possesses 13 enzymes not present in T. gondii and a homolog of an alpha-glucosidase (EC 3.2.1.20) that preferentially gives S. neurona the potential to use alternative carbon sources to help drive growth. Hence, our flux balance analysis showed that S. neurona is less reliant on the TCA cycle when it is grown in the presence of sucrose and that sucrose supplementation can increase parasite growth to 180% of its original rate, a capability that may be important for allowing the parasite to exploit new host niches. These findings serve to highlight subtle differences in pathway utilization that the two parasites may have adopted to optimize their distinct life cycle strategies.