Biochemical characterization and structural analysis of ulvan lyase from marine Alteromonas sp. reveals the basis for its salt tolerance
Biochemical characterization and structural analysis of ulvan lyase from marine Alteromonas sp. reveals the basis for its salt tolerance
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DOI：
10.1016/j.ijbiomac.2019.10.095
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发表时间：
2020-03-15
影响因子：
8.2
通讯作者：
Lu, Fuping
中科院分区：
文献类型：
--
作者：
Qin, Hui-Min;Gao, Dengke;Lu, Fuping
海洋大型藻类作为可再生的生物质来源已经获得了相当大的关注。石莼多糖是一种水溶性的阴离子多糖，其降解为可发酵的单糖具有生产生物乙醇或高价值食品添加剂的巨大潜力。来自Alteromonas sp.（AsPL）的石莼多糖裂解酶利用β-消除机制切割鼠李糖3-硫酸酯和葡萄糖醛酸之间的糖苷键，在非还原端形成不饱和的糖醛酸。AsPL在30-50 ° C的温度范围和7.5至9.5的pH值范围内具有活性。此外，AsPL被发现是嗜盐的，在高达2.5 M NaCl的存在下显示出高活性和稳定性。AsPL的表观K（m）和k（cat）值分别为3.19 +/- 0.37 mg mL（-1）和4.19 +/- 0.21 s（-1）。晶体结构分析表明，AsPL采用β螺旋桨折叠，在七个螺旋桨叶片中的每一个中都有四个反平行的β链。蛋白质表面的酸性残基和两个Ca ~（2+）配位位点有助于其耐盐性。石莼多糖裂解酶的研究在利用藻类资源生产生物燃料，减轻石油化工对环境的负担方面具有潜在的商业价值。(C)2019 Elsevier B. V.版权所有。
Marine macroalgae have gained considerable attention as renewable biomass sources. Ulvan is a watersoluble anionic polysaccharide, and its depolymerization into fermentable monosaccharides has great potential for the production of bioethanol or high-value food additives. Ulvan lyase from Alteromonas sp. (AsPL) utilizes a beta-elimination mechanism to cleave the glycosidic bond between rhamnose 3-sulfate and glucuronic acid, forming an unsaturated uronic acid at the non-reducing end. AsPL was active in the temperature range of 30-50 degrees C and pH values ranging from 7.5 to 9.5. Furthermore, AsPL was found to be halophilic, showing high activity and stability in the presence of up to 2.5 M NaCl. The apparent K(m )and k(cat) values of AsPL are 3.19 +/- 0.37 mg mL(-1) and 4.19 +/- 0.21 s(-1), respectively. Crystal structure analysis revealed that AsPL adopts a beta-propeller fold with four anti-parallel beta-strands in each of the seven propeller blades. The acid residues at the protein surface and two Ca2+ coordination sites contribute to its salt tolerance. The research on ulvan lyase has potential commercial value in the utilization of algal resources for biofuel production to relieve the environmental burden of petrochemicals. (C) 2019 Elsevier B.V. All rights reserved.