Structural features of the lysosomal hydrolase mannose 6-phosphate uncovering enzyme.
Structural features of the lysosomal hydrolase mannose 6-phosphate uncovering enzyme.
复制标题
溶酶体水解酶甘露糖 6-磷酸揭示酶的结构特征。
DOI：
10.1007/s10719-005-0846-8
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发表时间：
2005
影响因子：
3
通讯作者：
YoungJr,WilliamW
中科院分区：
文献类型：
--
作者：
Wei,Yuqiang;Yen,Ten-Yang;Cai,Jian;Trent,JohnO;Pierce,WilliamM;YoungJr,WilliamW
解覆盖酶(UCE)从溶酶体酶中去除N-乙酰氨基葡萄糖，以发现甘露糖6-磷酸(Man-6-P)决定簇，这是将这些酶靶向溶酶体所必需的。未能产生Man-6-P决定簇是溶酶体储存疾病的原因之一。尽管它在医学上很重要，但关于UCE的结构信息很少。在这份报告中，我们根据整合素αVβ3β链细胞外段的EFG-3和-4结构域的结构，建立了UCE管腔结构域的膜近端部分的模型。在这个模型中，UCE的EGF样结构域(残基285-345)被预测为形成一个杆状的茎区域，类似于高尔基糖基转移酶的茎区域。这根茎导致所提出的催化结构域(残基1-277)从高尔基膜延伸出去。建议的催化结构域的一部分(残基85-256)位于同源基团簇(COG)4632中，含有四种细菌蛋白，但与任何已知的真核蛋白都不是同源的。因此，UCE可能是由一个独特的催化域和一个共同的EGF样茎结构域融合而来的。我们通过质谱分析确定了该催化域的四个二硫键位于Cys2-Cys172、Cys66-Cys99、Cys83-Cys274和Cys258-Cys265之间。最后，我们确定了COS细胞中六个潜在的N-连接糖基化位点中的四个(ASN 159、ASN 165、ASN 247和ASN 317)是糖基化的。
The uncovering enzyme (UCE) removes N-acetylglucosamine from lysosomal enzymes to uncover the mannose 6-phosphate (Man-6-P) determinant necessary for targeting these enzymes to lysosomes. Failure to create the Man-6-P determinant is one cause of lysosomal storage diseases. Despite its medical importance, little structural information about UCE is available. In this report we have developed a model for the membrane proximal portion of the lumenal domain of UCE based on the structure of the EFG-3 and -4 domains of the extracellular segment of the beta chain of integrin α Vβ 3. In this model the EGF-like domains of UCE (residues 285–345) are predicted to form a rod-shaped stalk region, similar to the stem region in Golgi glycosyltransferases. This stalk causes the proposed catalytic domain (residues 1–277) to be extended away from the Golgi membrane. A portion of the proposed catalytic domain (residues 85-256) resides in Cluster of Orthologous Group (COG) 4632 with four bacterial proteins but is not homologous to any known eukaryotic proteins. Thus, UCE may have evolved from the fusion of a unique catalytic domain with a common EGF-like stalk domain. We have determined by mass spectrometry that the four disulfide bonds of the proposed catalytic domain are located between Cys2–Cys172, Cys66–Cys99, Cys83–Cys274, and Cys258–Cys265. Finally, we determined that four of the six potential N-linked glycosylation sites are glycosylated (Asn 159, Asn 165, Asn 247, and Asn 317) in COS cells.Published in 2005.