首页>
外文期刊>The biochemical journal
>Synthesis of paucimannose N-glycans by Caenorhabditis elegans requires prior actions of UDP-N-acetyl-d-glucosamine:alpha-3-d-mannoside beta1,2-N-acetylglucosaminyltransferase I, alpha3,6-mannosidase II and a specific membrane-bound beta-N-acetylglucosaminidase
【24h】
Synthesis of paucimannose N-glycans by Caenorhabditis elegans requires prior actions of UDP-N-acetyl-d-glucosamine:alpha-3-d-mannoside beta1,2-N-acetylglucosaminyltransferase I, alpha3,6-mannosidase II and a specific membrane-bound beta-N-acetylglucosaminidase
pWe have previously reported three iCaenorhabditis elegans/i genes (igly-12, gly-13/i and igly-14/i) encoding UDP-iN/i-acetyl-d-glucosamine:α-3-d-mannoside β1,2-iN/i-acetylglucosaminyltransferase I (GnT I), an enzyme essential for hybrid and complex N-glycan synthesis. GLY-13 was shown to be the major GnT I in worms and to be the only GnT I cloned to date which can act on [Manα1,6(Manα1,3)Manα1,6](Manα1,3)Manβ1, 4GlcNAcβ1,4GlcNAc-R, but not on Manα1,6(Manα1,3)Manβ1-iO/i-R substrates. We now report the kinetic constants, bivalent-metal-ion requirements, and optimal pH, temperature and Mnsup2+/sup concentration for this unusual enzyme. iC. elegans/i glycoproteins are rich in oligomannose (Mansub6–9/subGlcNAcsub2/sub) and ‘paucimannose’ Mansub3–5/subGlcNAcsub2/sub(±Fuc) N-glycans, but contain only small amounts of complex and hybrid N-glycans. We show that the synthesis of paucimannose Mansub3/subGlcNAcsub2/sub requires the prior actions of GnT I, α3,6-mannosidase II and a membrane-bound β-iN/i-acetylglucosaminidase similar to an enzyme previously reported in insects. The β-iN/i-acetylglucosaminidase removes terminal iN/i-acetyl-d-glucosamine from the GlcNAcβ1, 2Manα1,3Manβ- arm of Manα1,6(GlcNAcβ1,2Manα1,3) Manβ1,4GlcNAcβ1,4GlcNAc-R to produce paucimannose Mansub3/subGlcNAcsub2/sub N-glycan. iN/i-acetyl-d-glucosamine removal was inhibited by two iN/i-acetylglucosaminidase inhibitors. Terminal GlcNAc was not released from [Manα1,6(Manα1,3)Manα1,6] (GlcNAcβ1,2Manα1,3)Manβ1,4GlcNAcβ1,4GlcNAc-R nor from the GlcNAcβ1,2Manα1,6Manβ- arm. These findings indicate that GLY-13 plays an important role in the synthesis of N-glycans by iC. elegans/i and that therefore the worm should prove to be a suitable model for the study of the role of GnT I in nematode development./p
展开▼
机译：>我们之前已经报道了编码UDP- 基因（ gly-12，gly-13 和 gly-14 ） > N -乙酰基-d-氨基葡萄糖：α-3-d-甘露糖苷β1,2- N -乙酰基氨基葡萄糖基转移酶I（GnT I），这是杂种和复合N-聚糖的必需酶合成。 GLY-13被证明是蠕虫中的主要GnT I，并且是迄今为止唯一可以作用于[Manα1,6（Manα1,3）Manα1,6]（Manα1,3）Manβ1、4GlcNAcβ1、4GlcNAc的GnT I -R，但不在Manα1,6（Manα1,3）Manβ1- O -R底物上。现在，我们报告这种非常规酶的动力学常数，二价金属离子需求量以及最佳pH，温度和Mn 2 + 浓度。 C。线虫糖蛋白富含低聚甘露糖（Man 6-9 GlcNAc 2 ）和'paucimannose'Man 3-5-5 GlcNAc 2 （±Fuc）N-聚糖，但仅包含少量复杂的和杂合的N-聚糖。我们表明，合成paucimannose Man 3 GlcNAc 2 需要先有GnT I，α3,6-甘露糖苷酶II和膜结合的β- N的作用-乙酰氨基葡糖苷酶类似于先前在昆虫中报道的酶。 β- N -乙酰氨基葡萄糖苷酶可从Manα1,6（GlcNAcβ1,2Manα1,3）Manβ1的GlcNAcβ1、2Manα1、3Manβ-臂上除去末端 N -乙酰基-d-氨基葡萄糖，4GlcNAcβ1,4GlcNAc-R产生paucimannose Man 3 GlcNAc 2 N-聚糖。 Ni-乙酰基-d-氨基葡萄糖的去除被两种 N-乙酰基氨基葡萄糖苷酶抑制剂抑制。末端GlcNAc没有从[Manα1,6（Manα1,3）Manα1,6]（GlcNAcβ1,2Manα1,3）Manβ1,4GlcNAcβ1,4GlcNAc-R释放，也没有从GlcNAcβ1,2Manα1,6Manβ-臂释放。这些发现表明，GLY-13在由iC合成N-聚糖中起重要作用。线虫，因此该蠕虫应被证明是研究GnT I在线虫发育中的作用的合适模型。
展开▼
