N-Glycoproteomic Analysis of Botryococcus Braunii

We have performed an N-glycoproteomic analysis of the green microalgae Botryococcus braunii, a promising candidate for the production of biofuels, accumulating considerable amounts of hydrocarbon oils. Thereby, three different strains have been compared: Showa (Race B), AC761 (Race B) and CCALA778 (Race A) which differ in the type of produced hydrocarbons. In total, 517 unique N-glycosylated peptides have been identified analyzing intact N-glycopeptides as well as deglycosylated, 18O-labeled peptides. Intact N-glycopeptides that harbored N-acetylhexosamine (HexNAc) at the non-reducing end were identified. Surprisingly, these GnTI-dependent N-glycans were also found to be modified with (di)methylated hexose. This type of methylated GnTI-dependent N-glycans has not been described so far.

本研究对可大量积累烃类油脂、极具生物燃料生产潜力的绿色微藻布朗葡萄藻（Botryococcus braunii）开展了N-糖蛋白质组学分析。在此基础上，本研究比较了3株产烃类型各异的布朗葡萄藻菌株：Showa（B型）、AC761（B型）以及CCALA778（A型）。通过分析完整N-糖肽以及去糖基化、18O标记肽段，本研究共计鉴定得到517条唯一的N-糖基化肽段，同时鉴定出非还原端带有N-乙酰己糖胺（N-acetylhexosamine, HexNAc）的完整N-糖肽。值得注意的是，这类依赖GnTI（N-乙酰葡萄糖胺转移酶I）的N-聚糖还被观测到带有（二）甲基化己糖修饰，此类甲基化依赖GnTI的N-聚糖此前尚未见诸报道。