Unraveling the novel structure and biosynthetic pathway of O-linked glycans in the Golgi apparatus of the human pathogenic Yeast Cryptococcus neoformans

Dong Jik Lee, Yong-Sun Bahn, Hong Jin Kim, Seung Yeon Chung, Hyun Ah Kang

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

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 onlyhomolog 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 Saccharomy ces 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.

Original languageEnglish
Pages (from-to)1861-1873
Number of pages13
JournalJournal of Biological Chemistry
Volume290
Issue number3
DOIs
Publication statusPublished - 2015 Jan 16

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Cryptococcus neoformans
Biosynthetic Pathways
Golgi Apparatus
Yeast
Polysaccharides
Yeasts
Mannosyltransferases
Xylose
Mannose
Virulence
Cryptococcosis
Genes
Basidiomycota
T-cells
Glycoside Hydrolases
Oligosaccharides
Structural analysis
Saccharomyces cerevisiae
Salts
High Pressure Liquid Chromatography

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

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title = "Unraveling the novel structure and biosynthetic pathway of O-linked glycans in the Golgi apparatus of the human pathogenic Yeast Cryptococcus neoformans",
abstract = "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 onlyhomolog 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 Saccharomy ces 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.",
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Unraveling the novel structure and biosynthetic pathway of O-linked glycans in the Golgi apparatus of the human pathogenic Yeast Cryptococcus neoformans. / Lee, Dong Jik; Bahn, Yong-Sun; Kim, Hong Jin; Chung, Seung Yeon; Kang, Hyun Ah.

In: Journal of Biological Chemistry, Vol. 290, No. 3, 16.01.2015, p. 1861-1873.

Research output: Contribution to journalArticle

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AU - Lee, Dong Jik

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N2 - 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 onlyhomolog 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 Saccharomy ces 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.

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