Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification
Sulfated N-glycans from human immunoglobulin A (IgA) were recently discovered via glycomic approaches. However, their site-specific description is still pending. Certain N-glycan structures at specific N-glycosylation sites in IgA are crucial for microbial neutralization and effector functions. For...
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Frontiers Media S.A.
2025-08-01
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| Series: | Frontiers in Molecular Biosciences |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmolb.2025.1595173/full |
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| author | Frania J. Zuniga-Banuelos Frania J. Zuniga-Banuelos Greta Lemke Greta Lemke Marcus Hoffmann Udo Reichl Udo Reichl Erdmann Rapp Erdmann Rapp |
| author_facet | Frania J. Zuniga-Banuelos Frania J. Zuniga-Banuelos Greta Lemke Greta Lemke Marcus Hoffmann Udo Reichl Udo Reichl Erdmann Rapp Erdmann Rapp |
| author_sort | Frania J. Zuniga-Banuelos |
| collection | DOAJ |
| description | Sulfated N-glycans from human immunoglobulin A (IgA) were recently discovered via glycomic approaches. However, their site-specific description is still pending. Certain N-glycan structures at specific N-glycosylation sites in IgA are crucial for microbial neutralization and effector functions. For instance, sialylated N-glycans on the C-terminal tailpiece mediate anti-viral activity by interfering with sialic-acid-binding viruses. Sulfated N-glycan epitopes can be ligands for viral proteins and thus play a role in the immune response. In this study, we performed a site-specific screening for sulfated and other rare N-glycans in two commercially available human serum IgA samples employing an in-depth N-glycoproteomic approach, previously developed by us. We found evidence of complex-type and hybrid-type N-glycans containing sulfated N-acetylhexosamine (sulfated HexNAc) attached to the N-glycosylation sites in the tailpiece and the CH2 domain of both IgA subclasses. Also, complex-type N-glycan compositions bearing O-acetylated sialic acid were identified primarily at the tailpiece site. Surprisingly, N-glycans bearing glucuronic acid were identified in the commercial IgA samples, but from peptides of “contaminant” glycoproteins. A detailed comparison of the N-glycosylation profiles of human serum IgA samples from two suppliers showed such N-glycans with sulfated HexNAc consistently in higher abundance in the tailpiece region. These findings have not been described before for a site-specific glycopeptide analysis. Overall, our work provides strategies for performing a dedicated site-specific search for sulfated and O-acetylated N-glycans that can be easily transferred, e.g., to human IgA derived from mucosal tissues, milk, or saliva. We expect that a wider and deeper micro-heterogeneity description of clinically relevant glycoproteins, such as immunoglobulins, can expand the screening for biomarkers or treatment options. |
| format | Article |
| id | doaj-art-c40c85435cfa43d88dc6e2e418620540 |
| institution | DOAJ |
| issn | 2296-889X |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Molecular Biosciences |
| spelling | doaj-art-c40c85435cfa43d88dc6e2e4186205402025-08-20T03:16:03ZengFrontiers Media S.A.Frontiers in Molecular Biosciences2296-889X2025-08-011210.3389/fmolb.2025.15951731595173Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identificationFrania J. Zuniga-Banuelos0Frania J. Zuniga-Banuelos1Greta Lemke2Greta Lemke3Marcus Hoffmann4Udo Reichl5Udo Reichl6Erdmann Rapp7Erdmann Rapp8Bioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, GermanyglyXera GmbH, Magdeburg, GermanyBioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, GermanyBioprocess Engineering, Otto von Guericke University Magdeburg, Magdeburg, GermanyBioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, GermanyBioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, GermanyBioprocess Engineering, Otto von Guericke University Magdeburg, Magdeburg, GermanyBioprocess Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, GermanyglyXera GmbH, Magdeburg, GermanySulfated N-glycans from human immunoglobulin A (IgA) were recently discovered via glycomic approaches. However, their site-specific description is still pending. Certain N-glycan structures at specific N-glycosylation sites in IgA are crucial for microbial neutralization and effector functions. For instance, sialylated N-glycans on the C-terminal tailpiece mediate anti-viral activity by interfering with sialic-acid-binding viruses. Sulfated N-glycan epitopes can be ligands for viral proteins and thus play a role in the immune response. In this study, we performed a site-specific screening for sulfated and other rare N-glycans in two commercially available human serum IgA samples employing an in-depth N-glycoproteomic approach, previously developed by us. We found evidence of complex-type and hybrid-type N-glycans containing sulfated N-acetylhexosamine (sulfated HexNAc) attached to the N-glycosylation sites in the tailpiece and the CH2 domain of both IgA subclasses. Also, complex-type N-glycan compositions bearing O-acetylated sialic acid were identified primarily at the tailpiece site. Surprisingly, N-glycans bearing glucuronic acid were identified in the commercial IgA samples, but from peptides of “contaminant” glycoproteins. A detailed comparison of the N-glycosylation profiles of human serum IgA samples from two suppliers showed such N-glycans with sulfated HexNAc consistently in higher abundance in the tailpiece region. These findings have not been described before for a site-specific glycopeptide analysis. Overall, our work provides strategies for performing a dedicated site-specific search for sulfated and O-acetylated N-glycans that can be easily transferred, e.g., to human IgA derived from mucosal tissues, milk, or saliva. We expect that a wider and deeper micro-heterogeneity description of clinically relevant glycoproteins, such as immunoglobulins, can expand the screening for biomarkers or treatment options.https://www.frontiersin.org/articles/10.3389/fmolb.2025.1595173/fullimmunoglobulin A (IgA)mass spectrometryglycoproteomicsN-glycosylationoxonium marker ionssulfated N-glycans |
| spellingShingle | Frania J. Zuniga-Banuelos Frania J. Zuniga-Banuelos Greta Lemke Greta Lemke Marcus Hoffmann Udo Reichl Udo Reichl Erdmann Rapp Erdmann Rapp Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification Frontiers in Molecular Biosciences immunoglobulin A (IgA) mass spectrometry glycoproteomics N-glycosylation oxonium marker ions sulfated N-glycans |
| title | Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification |
| title_full | Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification |
| title_fullStr | Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification |
| title_full_unstemmed | Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification |
| title_short | Immunoglobulin A carries sulfated and O-acetylated N-glycans primarily at the tailpiece site – strategies for site-specific N-glycan identification |
| title_sort | immunoglobulin a carries sulfated and o acetylated n glycans primarily at the tailpiece site strategies for site specific n glycan identification |
| topic | immunoglobulin A (IgA) mass spectrometry glycoproteomics N-glycosylation oxonium marker ions sulfated N-glycans |
| url | https://www.frontiersin.org/articles/10.3389/fmolb.2025.1595173/full |
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