Endo-β-N-acetylglucosaminidases from Infant Gut-associated Bifidobacteria Release Complex N-glycans from Human Milk Glycoproteins
Endo-β-N-acetylglucosaminidases from Infant Gut-associated Bifidobacteria Release Complex N-glycans from Human Milk Glycoproteins
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DOI：
10.1074/mcp.m112.018119
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发表时间：
2012-09-01
影响因子：
7
通讯作者：
Mills, David A.
中科院分区：
文献类型：
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作者：
Garrido, Daniel;Nwosu, Charles;Mills, David A.
母乳喂养是指导婴儿出生前几个月肠道微生物区系组成的主要因素之一。这一过程在一定程度上是由高含量的人类乳寡糖形成的，这些低聚糖是双歧杆菌等糖类分解细菌的碳源。婴儿传播的双歧杆菌已经开发出各种分子策略来利用这些低聚糖作为碳源。我们推测，这些物种还与宿主糖蛋白中发现的N-葡聚糖相互作用，这些糖蛋白在结构上类似于人类乳汁中的游离寡糖。在某些长双歧杆菌亚种中发现了内切-β-N-乙酰氨基葡萄糖苷酶。Long um，B.long um亚种。婴儿和短双歧杆菌，它们的存在与这些菌株脱糖基糖蛋白的能力有关。婴儿芽孢杆菌ATCC 15697的一种内切糖苷酶EndoBI-1对糖基化蛋白中发现的所有主要类型的N-连接的多糖都有活性。其活性不受核心岩藻糖基化或广泛岩藻糖化、天线数或唾液酸化的影响，从人乳铁蛋白和免疫球蛋白A和G中释放出几个N-糖链，与该酶共同孵育后，整个母乳中也观察到广泛的N-脱糖作用。EndoBI-1活性部位的突变不会取消与N-糖基化蛋白的结合，该突变体特异性地识别人N-糖链的核心结构Man(3)GlcNAc(2)(α1-6Fuc)。EndoBI-1在婴儿芽孢杆菌中结构性表达，与人或牛乳铁蛋白孵育后，导致了与人类乳寡糖进口和消费相关的基因的诱导，这表明这些糖链之间存在连锁的调控机制。这项工作揭示了双歧杆菌与宿主N-糖链的一种前所未有的相互作用，并描述了一种对多种N-糖链类型具有广泛特异性的新型内切糖苷酶，这可能是糖蛋白质组学研究的有用工具。分子与细胞蛋白质组学11：10.1074/mcp.M112.018119,775-785,2012年。
Breastfeeding is one of the main factors guiding the composition of the infant gut microbiota in the first months of life. This process is shaped in part by the high amounts of human milk oligosaccharides that serve as a carbon source for saccharolytic bacteria such as Bifidobacterium species. Infant-borne bifidobacteria have developed various molecular strategies for utilizing these oligosaccharides as a carbon source. We hypothesized that these species also interact with N-glycans found in host glycoproteins that are structurally similar to free oligosaccharides in human milk. Endo-beta-N-acetylglucosaminidases were identified in certain isolates of Bifidobacterium longum subsp. longum, B. longum subsp. infantis, and Bifidobacterium breve, and their presence correlated with the ability of these strains to deglycosylate glycoproteins. An endoglycosidase from B. infantis ATCC 15697, EndoBI-1, was active toward all major types of N-linked glycans found in glycosylated proteins. Its activity was not affected by core fucosylation or extensive fucosylation, antenna number, or sialylation, releasing several N-glycans from human lactoferrin and immunoglobulins A and G. Extensive N-deglycosylation of whole breast milk was also observed after coincubation with this enzyme. Mutation of the active site of EndoBI-1 did not abolish binding to N-glycosylated proteins, and this mutant specifically recognized Man(3)GlcNAc(2)(alpha 1-6Fuc), the core structure of human N-glycans. EndoBI-1 is constitutively expressed in B. infantis, and incubation of the bacterium with human or bovine lactoferrin led to the induction of genes associated to import and consumption of human milk oligosaccharides, suggesting linked regulatory mechanisms among these glycans. This work reveals an unprecedented interaction of bifidobacteria with host N-glycans and describes a novel endoglycosidase with broad specificity on diverse N-glycan types, potentially a useful tool for glycoproteomics studies. Molecular & Cellular Proteomics 11: 10.1074/mcp.M112.018119, 775-785, 2012.