Discovery of an Internal α-1,3-Linkage-Containing Manno-Oligosaccharide in the O-Linked Cell Wall Mannan of Two Candida parapsilosis Complex Species via a Benanomicin A-Based Purification Method

Cell wall mannan samples were prepared from a single strain of each Candida parapsilosis complex species (C. parapsilosis sensu stricto, C. orthopsilosis, and C. metapsilosis) using benanomicin A, an antibiotic with lectin-like activity. Their O-linked oligosaccharides were subsequently obtained in good yield via β-elimination (alkaline treatment). From the mannan of C. parapsilosis sensu stricto, only short α-1,2-linked manno-oligosaccharides were obtained. In contrast, the mannans of C. orthopsilosis and C. metapsilosis additionally yielded a unique pentasaccharide, Manα1-2Manα1-3Manα1-2Manα1-2Man. Notably, this pentasaccharide, which contains an internal α-1,3-linked mannose residue, was recovered in appreciable amounts, whereas the corresponding tetrasaccharide (Manα1-3Manα1-2Manα1-2Man), a presumed biosynthetic intermediate, was barely detectable. This structure represents, to our knowledge, the first example of such a manno-oligosaccharide isolated from the O-linked domain of budding yeast cell wall mannans.