A deletion in the golgi alpha-mannosidase II gene of Caenorhabditis elegans results in unexpected non-wild-type N-glycan structures.
A deletion in the golgi alpha-mannosidase II gene of Caenorhabditis elegans results in unexpected non-wild-type N-glycan structures.
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DOI：
10.1074/jbc.m602878200
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发表时间：
2006-09-22
期刊：
影响因子：
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通讯作者：
Wilson IB
中科院分区：
文献类型：
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作者：
Paschinger K;Hackl M;Gutternigg M;Kretschmer-Lubich D;Stemmer U;Jantsch V;Lochnit G;Wilson IB
内质网和高尔基体中的 α-甘露糖苷酶对 N-连接寡糖的加工是植物和动物中保守的过程。通过 N-乙酰葡糖胺基转移酶 I 将 GlcNAc 残基转移至 Asn 结合的 Man5GlcNAc2 后，α-甘露糖苷酶 (EC 3.2.1.114) 去除一个 α1,3-连接的甘露糖残基和一个 α1,6-连接的甘露糖残基。在本研究中，我们从秀丽隐杆线虫中鉴定了相关的 α-甘露糖苷酶 II 基因（aman-2；F58H1.1），并检测了其天然和重组形式的活性。为了进行比较研究，克隆了编码 II 类甘露糖苷酶 aman-1 (F55D10.1) 和 aman-3 (F48C1.1) 的另外两个 cDNA，它们分别编码假定的溶酶体 α-甘露糖苷酶和 Co(II) 激活的 α-甘露糖苷酶。对 aman-2 突变株 N-聚糖结构的分析表明，α-甘露糖苷酶 II 活性的缺失会导致向野生型蠕虫中未见的结构转变（例如，组成为 Hex5-7HexNAc2-3Fuc2Me 的 N-聚糖）和杂合寡糖的积累。 aman-2 线虫中几乎不存在少量甘露糖苷聚糖，这也表明普遍缺乏 α-甘露糖苷酶 III 活性。我们假设线虫的糖基化途径具有巨大的灵活性，在标准实验室条件下，它不会影响糖型与野生型模式非常不同的线虫的生存能力。
The processing of N-linked oligosaccharides by α-mannosidases in the endoplasmic reticulum and Golgi is a process conserved in plants and animals. After the transfer of a GlcNAc residue to Asn-bound Man5GlcNAc2 by N-acetylglucosaminyltransferase I, an α-mannosidase (EC 3.2.1.114) removes one α1,3-linked and one α1,6-linked mannose residue. In the present study, we have identified the relevant α-mannosidase II gene (aman-2; F58H1.1) from Caenorhabditis elegans and have detected its activity in both native and recombinant forms. For comparative studies, the two other cDNAs encoding class II mannosidases aman-1 (F55D10.1) and aman-3 (F48C1.1) were cloned, which encode, respectively, a putative lysosomal α-mannosidase and a Co(II)-activated α-mannosidase. The analysis of the N-glycan structures of an aman-2 mutant strain demonstrates that the absence of α-mannosidase II activity results in a shift to structures not seen in wild-type worms (e.g., N-glycans with the composition Hex5-7HexNAc2-3Fuc2Me) and an accumulation of hybrid oligosaccharides. Paucimannosidic glycans are almost absent from aman-2 worms, indicative also of a general lack of α-mannosidase III activity. We hypothesise that there is a tremendous flexibility in the glycosylation pathway of C. elegans which does not impinge, under standard laboratory conditions, on the viability of worms with glycotypes very unlike the wild-type pattern.