Yagi Hirokazu, Saito Taiki, Guu Shih-Yun, Yamakawa Nao, Shimamura Shigeru, Kondo Sachiko, Yagi-Utsumi Maho, Takai Ken, Furukawa Jun-Ichi, Guérardel Yann, Khoo Kay-Hooi, Arakawa Kazuharu, Kato Koichi
Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan; Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Okazaki, Japan.
Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
Mol Cell Proteomics. 2025 Apr 28;24(6):100979. doi: 10.1016/j.mcpro.2025.100979.
We characterized the N-glycosylation profiles of anhydrobiotic tardigrades, Ramazzottius varieornatus and Hypsibius exemplaris, identifying high-mannose, paucimannose, and complex-type oligosaccharides, while hybrid-type glycans were undetectable. Notably, paucimannose-type oligosaccharides accounted for 39% of the N-glycans in R. varieornatus and 17% in H. exemplaris, with a substantial proportion of them exhibiting fucosylation of the innermost GlcNAc via an α1,6-linkage. This core fucosylation pattern, common to all animals, was observed alongside a distinctive glycosylation signature prominently observed in tardigrades: complex-type glycans lacking galactosylation but containing α1,3-fucosylated GlcNAc at non-reducing termini. This structure was more prevalent in H. exemplaris, with 22 out of 87 identified glycoproteins expressing the Fucα1,3-GlcNAc motif, including eight induced during anhydrobiosis. Key glycoproteins such as Cu/Zn-superoxide dismutase and papilin, implicated in oxidative stress protection and extracellular matrix remodeling, were among those modified. Comparative analyses reveal that non-reducing terminal α1,3-fucosylation in tardigrades is distinct from the mammalian Lewis X antigen and similar structures found in invertebrates, suggesting a unique substrate specificity of fucosyltransferases in these species. Genomic analysis identified homologs of FUT9 and FucTC, indicating potential candidates responsible for this glycosylation pattern. Our findings provide new insights into the molecular mechanisms of glycosylation in tardigrades and their relevance to their extreme stress tolerance.
我们对脱水生存的缓步动物——杂色马氏缓步虫和典型高生熊虫的N-糖基化谱进行了表征，鉴定出了高甘露糖型、寡甘露糖型和复合型寡糖，而未检测到杂合型聚糖。值得注意的是，寡甘露糖型寡糖在杂色马氏缓步虫的N-聚糖中占39%，在典型高生熊虫中占17%，其中很大一部分通过α1,6-连接在内层GlcNAc上表现出岩藻糖基化。这种所有动物共有的核心岩藻糖基化模式，与在缓步动物中显著观察到的独特糖基化特征同时出现：缺乏半乳糖基化但在非还原末端含有α1,3-岩藻糖基化GlcNAc的复合型聚糖。这种结构在典型高生熊虫中更为普遍，在87种已鉴定的糖蛋白中有22种表达Fucα1,3-GlcNAc基序，其中包括8种在脱水生存期间诱导产生的糖蛋白。参与氧化应激保护和细胞外基质重塑的关键糖蛋白，如铜/锌超氧化物歧化酶和鳞翅蛋白，都在这些被修饰的糖蛋白之中。比较分析表明，缓步动物中的非还原末端α1,3-岩藻糖基化不同于哺乳动物的Lewis X抗原以及在无脊椎动物中发现的类似结构，这表明这些物种中岩藻糖基转移酶具有独特的底物特异性。基因组分析鉴定出了FUT9和FucTC的同源物，表明它们可能是造成这种糖基化模式的候选基因。我们的研究结果为缓步动物糖基化的分子机制及其与极端应激耐受性的相关性提供了新的见解。
