Growth-dependent secretome of Candida utilis

Abstract

Recently, the food yeastCandida utilishas emerged as an excellent host for production of heterologous proteins. Since secretion of the recombinant product is advantageous for its purification, we characterized the secreted proteome ofC. utilis.Cells were cultivated to the exponential or stationary growth phase, and the proteins in the medium were identified by MS. In parallel, a draft genome sequence ofC. utilisstrain DSM 2361 was determined by massively parallel sequencing. Comparisons of protein and coding sequences established thatC. utilisis not a member of the CUG clade ofCandidaspecies. In total, we identified 37 proteins in the culture solution, 17 of which were exclusively present in the stationary phase, whereas three proteins were specific to the exponential growth phase. Identified proteins represented mostly carbohydrate-active enzymes associated with cell wall organization, while no proteolytic enzymes and only a few cytoplasmic proteins were detected. Remarkably, cultivation in xylose-based medium generated a protein pattern that diverged significantly from glucose-grown cells, containing the invertase Inv1 as the major extracellular protein, particularly in its highly glycosylated S-form (slow-migrating). Furthermore, cultivation without ammonium sulfate induced the secretion of the asparaginase Asp3. Comparisons of the secretome ofC. utiliswith those ofKluyveromyces lactisandPichia pastoris, as well as with those of the human fungal pathogensCandida albicansandCandida glabrata, revealed a conserved set of 10 and six secretory proteins, respectively.