Chemoenzymatic Synthesis of N‑glycan Positional Isomers and Evidence for Branch Selective Binding by Monoclonal Antibodies and Human C‑type Lectin Receptors

Here, we describe a strategy for the rapid preparation of pure positional isomers of complex N-glycans to complement an existing array comprising a larger number of N-glycans and smaller glycan structures. The expanded array was then employed to study context-dependent binding of structural glycan f...

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Bibliographic Details
Published in:ACS chemical biology 2018-08, Vol.13 (8), p.2269-2279
Main Authors: Echeverria, Begoña, Serna, Sonia, Achilli, Silvia, Vivès, Corinne, Pham, Julie, Thépaut, Michel, Hokke, Cornelis H, Fieschi, Franck, Reichardt, Niels-Christian
Format: Article
Language:English
Subjects:
Biochemistry, Molecular Biology
Life Sciences
Structural Biology
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Summary:Here, we describe a strategy for the rapid preparation of pure positional isomers of complex N-glycans to complement an existing array comprising a larger number of N-glycans and smaller glycan structures. The expanded array was then employed to study context-dependent binding of structural glycan fragments by monoclonal antibodies and C-type lectins. A partial enzymatic elongation of semiprotected core structures was combined with the protecting-group-aided separation of positional isomers by preparative HPLC. This methodology, which avoids the laborious chemical differentiation of antennae, was employed for the preparation of eight biantennary N-glycans with Galβ1,4GlcNAc (LN), GalNAcβ1,4GlcNAc (LDN), and GalNAcβ1,4­[Fucα1,3]­GlcNAc (LDNF) motifs presented on either one or both antennae. Screening of the binding specificities of three anti-LeX monoclonal IgM antibodies raised against S. mansoni glycans and three C-type lectin receptors of the innate immune system, namely DC-SIGN, DC-SIGNR, and LSECtin, revealed a surprising context-dependent fine specificity for the recognition of the glycan motifs. Moreover, we observed a striking selection of one individual positional isomer over the other by the C-type lectins tested, underscoring the biological relevance of the structural context of glycan elements in molecular recognition.
ISSN:1554-8929
1554-8937
DOI:10.1021/acschembio.8b00431