The Glyoxylate Cycle Is Involved in White-Opaque Switching in .

is a commensal yeast that inhabits the gastrointestinal tract of humans. The master regulator of the white-opaque transition has been implicated in the adaptation to this commensal status. A proteomic analysis of cells overexpressing this transcription factor () suggested an altered metabolism of carbon sources and a phenotypic analysis confirmed this alteration. The cells are deficient in using trehalose and xylose and are unable to use 2C sources, which is consistent with a reduction in the amount of Icl1, the isocitrate lyase enzyme. The mutants overexpressing are deficient in the production of phloxine B positive cells, a main characteristic of opaque cells, a phenotype also observed in mating type hemizygous cells, suggesting the involvement of Icl1 in the adaptation to the commensal state. In fact, cells have reduced fitness in mouse gastrointestinal tract as compared with essentially isogenic heterozygous / but overproduction of in an mutant does not restore fitness. These results implicate the glyoxylate shunt in the adaptation to commensalism of by mechanisms that are partially independent of .