在这里，小组报道了一种金藻——丹麦Ochromonas danica的管状乳螺管的低温电镜结构，其中大量的N-和O-聚糖以1.8-2.2Å的分辨率被分解。除了高甘露糖和复杂的n-聚糖，课题组人员在Ala-Asn-Asp （and）基序上发现了一个非规范的N-聚糖。表面尖峰包含密集的覆盖PSXX四肽重复序列的O-聚糖，每个重复序列有两个聚糖连接在三羟基化脯氨酸上，一个连接在丝氨酸上。除了各种类型的糖及其共价修饰剂，水分子（占溶解体积的10%）和阳离子也被清楚地分解并介导结构组装。他们的研究为研究高阶生物组装中的聚糖折叠建立了一个框架。
据了解，多糖的化学复杂性和非模板生物合成对建立序列-结构关系提出了重大挑战。
附：英文原文
Title: Structural N- and O-glycans revealed by high-resolution cryo-EM analysis of tubular mastigonemes
Author: 黄隽豪)
Issue&Volume: 2026-04-23
Abstract: 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 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: aef4958
Source: https://www.science.org/doi/10.1126/science.aef4958