Free-oligosaccharide control in the yeast Saccharomyces cerevisiae:: roles for peptide:N-glycanase (Png1p) and vacuolar mannosidase (Ams1p)
Free-oligosaccharide control in the yeast Saccharomyces cerevisiae:: roles for peptide:N-glycanase (Png1p) and vacuolar mannosidase (Ams1p)
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DOI：
10.1042/bj20030384
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发表时间：
2003-08-01
影响因子：
4.1
通讯作者：
Moore, SEH
中科院分区：
文献类型：
--
作者：
Chantret, I;Frénoy, JP;Moore, SEH
游离寡糖 (fOS) 是在哺乳动物细胞糖蛋白生物合成过程中产生的。在这里，我们报告了酿酒酵母中这些结构的起源和命运。用[2-H-3]甘露糖([2-H-3]Man)进行代谢放射性标记30分钟后，Man(8)GlcNAc(2)被鉴定为该生物体中的主要fOS，并且发现与该结构相关的放射性大约相当于与糖蛋白N连接的相同结构相关的放射性的1%。尽管引起与脂联寡糖相关的放射性增加四倍，但蛋白质合成抑制剂放线菌酮可阻断 [2-H-3]Man 掺入内-β-D-N-乙酰葡糖胺 H 敏感的 N-聚糖和 fOS。研究发现，由 PNG1 基因编码的肽：N-聚糖酶是在蛋白质糖基化期间和之后不久产生大部分酵母 fOS 所必需的。使用缺乏液泡α-甘露糖苷酶的ams1Delta菌株揭示了这种酶是与生长相关的fOS分解代谢缓慢的原因。本文首次描述了完整酿酒酵母中 fOS 的形成，并且通过证明 fOS 被液泡甘露糖苷酶降解，已经确定了这种人们知之甚少的酶的新功能。
Free oligosaccharides (fOS) are generated during glycoprotein biosynthesis in mammalian cells. Here we report on the origin and fate of these structures in the yeast Saccharomyces cerevisiae. After metabolic radiolabelling with [2-H-3]mannose ([2-H-3]Man) for 30 min, Man(8)GlcNAc(2) was identified as the predominant fOS in this organism, and radioactivity associated with this structure was found to correspond to approximate to1 % of that associated with the same structure N-linked to glycoprotein. Despite provoking a fourfold increase in radioactivity associated with lipid-linked oligosaccharide, the protein-synthesis inhibitor cycloheximide blocked [2-H-3]Man incorporation into both endo-beta-D-N-acetylglucosamine H-sensitive N-glycans and fOS. Peptide:N-glycanase, encoded by the PNG1 gene, was found to be required for the generation of a large proportion of yeast fOS during, and soon after, protein glycosylation. Use of an ams1Delta strain deficient in the vacuolar alpha-mannosidase revealed this enzyme to be responsible for the slow growth-associated catabolism of fOS. The present paper constitutes the first description of fOS formation in intact S. cerevisiae, and, with the demonstration that fOS are degraded by the vacuolar mannosidase, a novel function for this poorly understood enzyme has been identified.