The basic components of central carbon metabolism have been identified in many species, yet little is known at the systems level about the function and evolution of different metabolic states. To address this, Romelie characterized the contribution of two pathways (the glyoxylate cycle and the pentose phosphate pathway) to central carbon metabolism in budding yeast.
Romelie and her mentors studied two strains of yeast, each lacking one critical enzyme: mls1 from the glyoxylate cycle, and zwf1 from the pentose phosphate pathway. She compared global expression profiles of the two yeast mutant strains to wild-type yeast. Each mutant displayed genes whose expression patterns were uncorrelated to wild-type; of those, 106 were common among both mutants. 91 of those had expression patterns that were similar between the two mutant strains, and 15 had opposite expression patterns. This finding reveals previously unexpected connectivity between the glyoxylate cycle and the pentose phosphate pathway.