Substrate specificity of alpha-1,6-mannosyltransferase that initiates N-linked mannose outer chain elongation in Saccharomyces cerevisiae
Substrate specificity of alpha-1,6-mannosyltransferase that initiates N-linked mannose outer chain elongation in Saccharomyces cerevisiae
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DOI：
10.1016/s0014-5793(97)00634-0
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发表时间：
1997-08-04
期刊：
影响因子：
3.5
通讯作者：
Jigami, Y
中科院分区：
文献类型：
--
作者：
Nakayama, K;NakanishiShindo, Y;Jigami, Y
酵母酵母（Saccharomyces cerevisiae）的OCH1基因编码n链寡糖外链延伸所必需的甘露糖基转移酶，以pyridylaminated Man(8)GlcNAc(2) (Man（8)GlcNAc(2)-PA）为受体，在HPLC上测定了OCH1基因产物（Och1p）的甘露糖基转移酶活性，并在Man(9)GlcNAc(2)-PA对应的保留时间观察了反应产物。h -1核磁共振和快原子轰击质谱法；Man(9)GlcNAc(2)-PA的片段化分析表明，附加的甘露糖在甘露糖外链延伸起始位点与α -1,6键连接，利用各种高甘露糖型低聚糖作为受体考察了Och1p的底物特异性，Man(8)GlcNAc(2)是Och1p的最佳受体。Man(8)GlcNAc(2)失去一个或两个α -1,2-甘露糖糖降低了甘露糖基转移酶的活性，Man(5)GlcNAc(2)完全缺乏α -1,2-甘露糖糖残基不能作为受体，Man(8)GlcNAcOH通过还原末端GlcNAc残基还原一个开糖环不能作为Och1p的受体，α -1,6分支上三个甘露糖的损失也降低了Och1p的活性。这些结果表明，Och1p是一种起始特异性α -1,6-甘露糖基转移酶，它需要Man(8)GlcNAc的完整结构才能有效地起始甘露糖外链。(C) 1997年欧洲生化学会联合会。
Yeast Saccharomyces cerevisiae OCH1 gene encodes the mannosyltransferase that is essential for the outer chain elongation of N-linked oligosaccharides, Mannosyltransferase activity of OCH1 gene product (Och1p) was measured on HPLC by using pyridylaminated Man(8)GlcNAc(2) (Man(8)GlcNAc(2)-PA) as an acceptor and the reaction product was observed at the retention time corresponding to Man(9)GlcNAc(2)-PA. H-1-NMR and fast atom bombardment mass spectrometry (FAB-R;IS) fragmentation analysis of Man(9)GlcNAc(2)-PA showed that the additional mannose was attached with an alpha-1,6 linkage at the site where mannose outer chain elongation initiates, Substrate specificity of Och1p was investigated by using various high mannose-type oligosaccharides as accepters, Man(8)GlcNAc(2) was the best acceptor for Och1p, The loss of one or two alpha-1,2-mannoses from Man(8)GlcNAc(2) reduced the mannosyltransferase activity and the Man(5)GlcNAc(2) completely lacking alpha-1,2-mannose residues did not serve as an acceptor, Man(8)GlcNAcOH that involves an open sugar ring by reduction of reducing terminal GlcNAc residue did not serve as an acceptor for Och1p, The loss of three mannoses at the alpha-1,6-branch also reduced the Och1p activity, These results suggest that Och1p is an initiation specific alpha-1,6-mannosyltransferase that requires the intact structure of Man(8)GlcNAc for efficient mannose outer chain initiation. (C) 1997 Federation of European Biochemical Societies.