Structure and Antigenicity of the Mannans ofCandida famataandCandida saitoana:Comparative Study with the Mannan ofCandida guilliermondii

The chemical structure of the mannans of antigenic factor 9-expressing yeast,Candida famataandCandida saitoana,was analyzed by acetolysis and NMR. The structural study of the oligosaccharides and mannans using one- and two-dimensional NMR indicated that the mannan ofC. saitoanacontains a third type of β-1,2-linked mannose unit. On the other hand, the mannan ofC. famatadoes not contain any β-1,2-linked mannose units. The mannan ofC. saitoanagave two groups of β-1,2 linkage-containing oligosaccharides by acetolysis. One contains one β-1,2-linked mannose unit and the other contains two consecutive β-1,2-linked mannose units at the nonreducing terminal. The inhibition of the reactivity of factor 9 serum on an enzyme-linked immunosorbent assay (ELISA) with these oligosaccharides indicated that the inhibition activity of the former oligosaccharide is 1/20 of that of the latter ones. The ELISA of the mannans ofCandida guilliermondii, C. saitoana,andSaccharomyces kluyveri,all of which contain the third type of β-1,2-linked mannose unit, indicated that Manβ1 → 2Manβ1 → 2Manα1 → 3Manα1 → works as the antigenic factor 9 but Manβ1 → 2Manα1 → 3Manα1 → weakly behaves as both antigenic factors 6 and 9. The epitope structures of the side chain oligosaccharides agreed well with that proposed from the 2D-HOHAHA spectra of the mannans. This result demonstrates the usefulness of the H-1–H-2-correlated cross-peak pattern, which was reported in a preceding paper (Shibata, N., Akagi, R., Hosoya, T., Kawahara, K., Suzuki, A., Ikuta, K., Kobayashi, H., Hisamichi, K., Okawa, Y., and Suzuki, S. (1996)J. Biol. Chem.271, 9259–9266) for the determination of the epitope structure ofCandidamannans without any chemical fragmentation.