Structural N- and O-glycans revealed by high-resolution cryo-EM analysis of tubular mastigonemes
Summary
The chemical complexity and non-templated biosynthesis of glycans have posed significant challenges for establishing sequence-structure relationships. Here we report cryo-EM structures of tubular mastigonemes from a golden alga species, Ochromonas danica, in which a large number of N- and O-glycans are resolved at 1.8-2.2 Å resolution. Beyond high-mannose and complex N-glycans, we identify a non-canonical N-glycan on the Ala-Asn-Asp (AND) motif. The surface spikes comprise dense O-glycans
Content
# Structural N- and O-glycans revealed by high-resolution cryo-EM analysis of tubular mastigonemes
*Published: 2026 Apr 23*
The chemical complexity and non-templated biosynthesis of glycans have posed
significant challenges for establishing sequence-structure relationships. Here
we report cryo-EM structures of tubular mastigonemes from a golden alga species,
Ochromonas danica, in which a large number of N- and O-glycans are resolved at
1.8-2.2 Å resolution. Beyond high-mannose and complex N-glycans, we identify a
non-canonical N-glycan on the Ala-Asn-Asp (AND) motif. The surface spikes
comprise dense O-glycans coating PSXX tetrapeptide repeats, with two glycans
linked on trihydroxylated proline and one on serine per repeat. In addition to
various types of sugars and their covalent modifiers, water molecules (>10% of
resolved volume) and cations are clearly resolved and mediate the structural
assembly. Our study establishes a framework for investigating glycan folding in
high-order biological assemblies.
DOI: 10.1126/science.aef4958