变铅青链霉菌TK24中新型硫酸软骨素裂解酶的发现与功能解析

Discovery and functional characterization of a novel chondroitinase from Streptomyces lividans TK24

摘要:

目的 硫酸软骨素裂解酶是制备低分子量硫酸软骨素的关键工具，但现有酶制剂难以满足多样化应用需求，因此需要发掘更多新型硫酸软骨素裂解酶。方法 从模式菌株变铅青链霉菌TK24中发现并鉴定了一种新型PL8家族硫酸软骨素裂解酶SlChase。经大肠杆菌异源表达与纯化后，获得可溶性的高活性SlChase重组酶。结果 该酶在30-40 ℃、pH 5.5-6.5范围内均保持较高活性，在4 ℃具有良好的长期稳定性；Mg²⁺与二硫苏糖醇(dithiothreitol, DTT)可轻微促进其活性，而Zn²⁺、Fe³⁺等金属离子则对该酶活性具有抑制作用。值得注意的是，SlChase对非硫酸化软骨素(CS-0S)表现出较好活性，对硫酸软骨素A/C的活性则显著降低。结论 SlChase的发现不仅丰富了PL8家族多糖裂解酶的多样性，也为非硫酸化软骨素的特异性降解提供了新型工具酶，在糖生物学研究及相关生物催化领域具有潜在应用价值。同时，SlChase的发现也为链霉菌酶学资源的开发利用提供了新的范例。

Abstract:

Objective Chondroitinases are crucial enzymes for the preparation of low-molecular-weight chondroitin sulfate (CS), yet the existing enzymes are insufficient to meet the demands of diverse applications, highlighting the need to discover novel chondroitinases with enhanced properties.Methods A novel chondroitinase belonging to the polysaccharide lyase family 8 (PL8), designated SlChase, was discovered and identified from the model strain Streptomyces lividans TK24. Following heterologous expression in Escherichia coli and the subsequent purification, a soluble and highly active recombinant SlChase was successfully obtained.Results This enzyme exhibited substantial activity within the temperature range of 30-40 ℃ and pH range of 5.5-6.5, and demonstrated excellent long-term stability during storage at 4 ℃. Mg²⁺ and dithiothreitol (DTT) moderately enhanced its catalytic activity, whereas metal ions including Zn²⁺ and Fe³⁺ exerted inhibitory effects on its activity. Notably, SlChase displayed prominent activity towards unsulfated chondroitin (CS-0S), whereas its catalytic activity towards chondroitin sulfate A/C was drastically decreased.Conclusion The discovered SlChase not only expands the diversity of PL8 family enzymes but also affords a novel enzymatic tool for the specific degradation of unsulfated chondroitin, with promising applications in glycoscience research and related biocatalytic processes. Furthermore, this study provides a paradigm for the exploration and utilization of enzymatic resources derived from Streptomyces spp.