Structure of a human lysosomal sulfatase
Structure of a human lysosomal sulfatase
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DOI：
10.1016/s0969-2126(97)00185-8
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发表时间：
1997-02-15
期刊：
影响因子：
5.7
通讯作者：
Guss, JM
中科院分区：
文献类型：
--
作者：
Bond, CS;Clements, PR;Guss, JM
背景：硫酸酯酶催化多种底物(包括糖胺聚糖、糖脂和类固醇)的硫酸水解酯，硫酸盐酶玻璃中有足够的共同序列相似性，表明它们具有共同的结构。参与糖胺-葡聚糖降解的特定溶酶体硫酸酯酶缺乏导致罕见的遗传性临床疾病，称为粘多糖病。在多重硫酸酯酶缺乏症患者中，所有的硫酸酯酶都是无效的，因为特定活性部位的半胱氨酸残基没有发生必要的翻译后修饰为氧丙氨酸。结果：N-乙酰半乳糖胺-4-硫酸酯酶的晶体结构在2.5埃分辨率下得到了解析和精炼，其结构具有两个结构域，其中较大的结构域属于α/β类蛋白质并含有活性中心，晶体中的酶活性中心包含一些迄今未被描述的特征。活性中心半胱氨酸残基Cys91是醛物种氧丙氨酸的硫酸盐衍生物。硫酸盐与以前未被检测到的金属离子结合，我们已经确定了酶的钒酸抑制形式的结构，这个结构表明钒酸取代了活性部位的硫酸盐，钒酸与蛋白质共价连接，给出了浸泡在单糖N-乙酰半乳糖胺中的晶体的初步数据，其结构形成了酶的产物络合物。结论：N-乙酰半乳糖胺-4-硫酸酯酶的结构揭示了硫酸盐家族中保守的残基参与了活性部位的钙离子和硫酸酯的稳定。这暗示了硫酸盐酶家族的一个原型折叠。对翻译后修饰的高度保守的半胱氨酸残基具有催化作用。尽管之前发现的序列与已知结构的任何蛋白质都没有任何相似之处，但包含该活性部位的大的硫酸盐酶结构域与碱性磷酸酶非常相似：硫酸盐酶中的钙离子叠加在碱性磷酸酶中的一个锌离子上，而Cys91的硫酸酯叠加在碱性磷酸酶活性部位中的磷酸根离子上。
Background: Sulfatases catalyze the hydrolysis of sulfuric acid esters from a wide variety of substrates including glycosaminoglycans, glycolipids and steroids, There is sufficient common sequence similarity within the Glass of sulfatase enzymes to indicate that they have a common structure. Deficiencies of specific lysosomal sulfatases that are involved in the degradation of glycosamino-glycans lead to rare inherited clinical disorders termed mucopolysaccharidoses. In sufferers of multiple sulfatase deficiency, all sulfatases are inactive because an essential posttranslational modification of a specific active-site cysteine residue to oxo-alanine does not occur. Studies of this disorder have contributed to location and characterization of the sulfatase active site, To understand the catalytic mechanism of sulfatases, and ultimately the determinants of their substrate specificities, we have determined the structure of N-acetylgalactosamine-4-sulfatase.Results: The crystal structure of the enzyme has been solved and refined at 2.5 Angstrom resolution using data recorded at both 123K and 273K, The structure has two domains, the larger of which belongs to the alpha/beta class of proteins and contains the active site, The enzyme active site in the crystals contains several hitherto undescribed features. The active-site cysteine residue, Cys91, is found as the sulfate derivative of the aldehyde species, oxo-alanine. The sulfate is bound to a previously undetected metal ion, which we have identified as calcium, The structure of a vanadate-inhibited form of the enzyme has also been solved, and this structure shows that vanadate has replaced sulfate in the active site and that the vanadate is covalently linked to the protein, Preliminary data is presented for crystals soaked in the monosaccharide N-acetylgalactosamine, the structure of which forms a product complex of the enzyme.Conclusions: The structure of N-acetylgalactosamine-4-sulfatase reveals that residues conserved amongst the sulfatase family are involved in stabilizing the calcium ion and the sulfate ester in the active site. This suggests an archetypal fold for the family of sulfatases. A catalytic role is proposed for the posttranslationally modified highly conserved cysteine residue. Despite a lack of any previously detectable sequence similarity to any protein of known structure, the large sulfatase domain that contains the active site closely resembles that of alkaline phosphatase: the calcium ion in sulfatase superposes on one of the zinc ions in alkaline phosphatase and the sulfate ester of Cys91 superposes on the phosphate ion found in the active site of alkaline phosphatase.