Lee DJ, Bahn YS, Kim HJ, Chung SY, Kang HA Unraveling the novel structure and biosynthetic pathway of O-linked glycans in the Golgi apparatus of the human pathogenic yeast Cryptococcus neoformans Journal of Biological Chemistry290(3) (2015)
1861-1873
NCBI PubMed ID:25477510 Publication DOI:10.1074/jbc.M114.607705 Journal NLM ID:2985121R Publisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology Correspondence: Kang HA <hyunkangcau.ac.kr> Institutions: College of Pharmacy, Chung-Ang University, Seoul, South Korea, Department of Life Science, Center for Fungal Pathogenesis, Yonsei University, Seoul, South Korea, Department of Biotechnology, Center for Fungal Pathogenesis, Yonsei University, Seoul, South Korea
Cryptococcus neoformans is an encapsulated basidiomycete causing cryptococcosis in immunocompromised humans. The cell surface mannoproteins of C. neoformans were reported to stimulate the host T-cell response and to be involved in fungal pathogenicity; however, their O-glycan structure is uncharacterized. In this study, we performed a detailed structural analysis of the O-glycans attached to cryptococcal mannoproteins using HPLC combined with exoglycosidase treatment and showed that the major C. neoformans O-glycans were short manno-oligosaccharides that were connected mostly by α1,2-linkages but connected by an α1,6-linkage at the third mannose residue. Comparison of the O-glycan profiles from wild-type and uxs1Δ mutant strains strongly supports the presence of minor O-glycans carrying a xylose residue. Further analyses of C. neoformans mutant strains identified three mannosyltransferase genes involved in O-glycan extensions in the Golgi. C. neoformans KTR3, the only homolog of the Saccharomyces cerevisiae KRE2/MNT1 family genes, was shown to encode an α1,2-mannosyltransferase responsible for the addition of the second mannose residue via an α1,2-linkage to the major O-glycans. C. neoformans HOC1 and HOC3, homologs of the Saccharomyces cerevisiae OCH1 family genes, were shown to encode α1,6-mannosyltransferases that can transfer the third mannose residue, via an α1,6-linkage, to minor O-glycans containing xylose and to major O-glycans without xylose, respectively. Moreover, the C. neoformans ktr3Δ mutant strain, which displayed increased sensitivity to SDS, high salt, and high temperature, showed attenuated virulence in a mouse model of cryptococcosis, suggesting that the extended structure of O-glycans is required for cell integrity and full pathogenicity of C. neoformans
Methods: PCR, DNA techniques, biological assays, HPLC, enzymatic digestion, hydrazinolysis, cell growth, dialysis, mutagenesis, derivatization, evaporation, centrifugation, staining Enzymes that release or process the structure: Pmt1p, Pmt2p, Pmt4p, Hoc1p (CNAG_05836)
Related record ID(s): 48326, 48327, 48328, 48329, 48331, 48332, 48333 NCBI Taxonomy refs (TaxIDs):235443 Reference(s) to other database(s): GTC:G26839NK Show glycosyltransferases
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