Arylsulfatase K, a Novel Lysosomal Sulfatase
Arylsulfatase K, a Novel Lysosomal Sulfatase
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DOI：
10.1074/jbc.m113.499541
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发表时间：
2013-10-18
影响因子：
4.8
通讯作者：
Dierks, Thomas
中科院分区：
文献类型：
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作者：
Wiegmann, Elena Marie;Westendorf, Eva;Dierks, Thomas
背景：人类硫酸酯酶在生理学中起着关键作用，在缺乏或调节不当的情况下会导致许多病理情况。结果：ARSK广泛表达，定位于溶酶体，在酸性pH条件下具有芳基硫酸酯酶活性。结论：ARSK是一种作用于普遍底物上的新型溶酶体硫酸酯酶。意义：ARSK在溶酶体的降解中发挥作用，可能是糖胺多聚糖的降解，并且很可能与一种非分类的溶酶体储存障碍有关。人类硫酸酯酶家族有17个成员，其中13个已被生化表征。这些酶特异地降解糖胺多聚糖、硫代脂肪或类固醇硫酸盐中的硫酸酯，从而在细胞降解、细胞信号传递和激素调节中发挥关键作用。硫酸酶活性的丧失与严重的病理生理状况有关，如溶酶体储存障碍、发育异常或癌症。该家族的一个新成员，芳基硫酸酯酶K(Arsk)，通过其保守的硫酸酯酶特征序列指导硫酸酯酶中催化的甲酰甘氨酸残基的翻译后生成而被生物信息学鉴定。然而，ARSK与其他人类硫酸盐酶的总体序列同源性很低(18-22%)。在这里，我们证明了ARSK确实显示了对芳基硫酸盐假底物的脱硫活性。当在人类细胞中表达时，检测到Arsk是一种68 kDa的糖蛋白，携带至少四种复合型和高甘露糖型的N-糖链。精制的ARSK生成对硝基邻苯二酚和对硝基苯硫酸酯。这种活性依赖于半胱氨酸80，半胱氨酸被证实可以转化为甲酰甘氨酸。动力学参数与几种溶酶体硫酸酯酶降解硫酸氨基葡聚糖的动力学参数相似。最适的酸性pH(约4.6)和与LAMP1的共定位证实了Arsk的溶酶体功能。此外，它还携带甘露糖6-磷酸，表明溶酶体通过甘露糖6-磷酸受体进行分选。在所有被测试的组织中都发现了Arsk mRNA的表达，这表明在Arsk缺乏的情况下，存在普遍存在的生理底物和迄今未分类的溶酶体储存障碍，就像之前对所有其他溶酶体硫酸酯酶所显示的那样。
Background: Human sulfatases play key roles in physiology and cause numerous pathological conditions upon deficiency/misregulation. Results: ARSK is ubiquitously expressed, localizes to lysosomes, and shows arylsulfatase activity at acidic pH. Conclusion: ARSK is a novel lysosomal sulfatase acting on a ubiquitous substrate. Significance: ARSK functions in lysosomal degradation, possibly of glycosaminoglycans, and, in all probability, is associated with a non-classified lysosomal storage disorder.The human sulfatase family has 17 members, 13 of which have been characterized biochemically. These enzymes specifically hydrolyze sulfate esters in glycosaminoglycans, sulfolipids, or steroid sulfates, thereby playing key roles in cellular degradation, cell signaling, and hormone regulation. The loss of sulfatase activity has been linked to severe pathophysiological conditions such as lysosomal storage disorders, developmental abnormalities, or cancer. A novel member of this family, arylsulfatase K (ARSK), was identified bioinformatically through its conserved sulfatase signature sequence directing posttranslational generation of the catalytic formylglycine residue in sulfatases. However, overall sequence identity of ARSK with other human sulfatases is low (18-22%). Here we demonstrate that ARSK indeed shows desulfation activity toward arylsulfate pseudosubstrates. When expressed in human cells, ARSK was detected as a 68-kDa glycoprotein carrying at least four N-glycans of both the complex and high-mannose type. Purified ARSK turned over p-nitrocatechol and p-nitrophenyl sulfate. This activity was dependent on cysteine 80, which was verified to undergo conversion to formylglycine. Kinetic parameters were similar to those of several lysosomal sulfatases involved in degradation of sulfated glycosaminoglycans. An acidic pH optimum (approximate to 4.6) and colocalization with LAMP1 verified lysosomal functioning of ARSK. Further, it carries mannose 6-phosphate, indicating lysosomal sorting via mannose 6-phosphate receptors. ARSK mRNA expression was found in all tissues tested, suggesting a ubiquitous physiological substrate and a so far non-classified lysosomal storage disorder in the case of ARSK deficiency, as shown before for all other lysosomal sulfatases.