Liu Guanchen, Shen Jingjing, Chang Yaoguang, Mei Xuanwei, Chen Guangning, Zhang Yuying, Xue Changhu
College of Food Science and Engineering, Ocean University of China, 5 Yushan Road, Qingdao 266003, China.
College of Food Science and Engineering, Ocean University of China, 5 Yushan Road, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao 266237, China.
Carbohydr Polym. 2023 Apr 15;306:120591. doi: 10.1016/j.carbpol.2023.120591. Epub 2023 Jan 16.
Sulfated fucans are important marine polysaccharides with various biological and biomedical activities. Fucanases are favorable tools to establish the structure-activity relationships of sulfated fucans. Herein, gene fun174A was discovered from the genome of marine bacterium Wenyingzhuangia aestuarii OF219, and none of the pre-defined glycosidic hydrolase domains were predicted in the protein sequence of Fun174A. Recombinant Fun174A demonstrated a low optimal reaction pH at 5.5. It might degrade sulfated fucans in an endo-processive manner. Glycomics and NMR analyses proved that it specifically hydrolyzed α-1,3-l-fucoside bonds between 2-O-sulfated and non-sulfated fucose residues in the sulfated fucan from sea cucumber Isostichopus badionotus. D119, E120 and E218 were critical for the activity of Fun174A, as identified by site-directed mutagenesis. Three homologs of Fun174A were confirmed to exhibit endo-1,3-fucanase activities. The novelty on sequences of Fun174A and its homologs reveals a new glycoside hydrolase family, GH174.
硫酸化岩藻聚糖是具有多种生物学和生物医学活性的重要海洋多糖。岩藻聚糖酶是建立硫酸化岩藻聚糖构效关系的有利工具。在此，从海洋细菌河口文营庄氏菌OF219的基因组中发现了基因fun174A，在Fun174A的蛋白质序列中未预测到任何预定义的糖苷水解酶结构域。重组Fun174A在pH 5.5时表现出较低的最佳反应pH值。它可能以内切加工的方式降解硫酸化岩藻聚糖。糖组学和核磁共振分析证明，它特异性水解来自糙海参的硫酸化岩藻聚糖中2-O-硫酸化和非硫酸化岩藻糖残基之间的α-1,3-L-岩藻糖苷键。通过定点诱变确定，D119、E120和E218对Fun174A的活性至关重要。已证实Fun174A的三个同源物具有内切1,3-岩藻聚糖酶活性。Fun174A及其同源物序列的新颖性揭示了一个新的糖苷水解酶家族，即GH174。
