Sun Guiqin, Yu Xiang, Bao Celimuge, Wang Lei, Li Meng, Gan Jianhua, Qu Di, Ma Jinbiao, Chen Li
From the Key Laboratory of Medical Molecular Virology, Ministry of Education and Health, Shanghai Medical College, Fudan University, Shanghai 200032, China, Zhejiang Chinese Medical University, Hangzhou 310053, China.
the State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, School of Life Sciences, Fudan University, Shanghai 200438, China.
J Biol Chem. 2015 Mar 20;290(12):7452-62. doi: 10.1074/jbc.M114.605493. Epub 2015 Jan 22.
Peptide:N-glycosidase (PNGase) F, the first PNGase identified in prokaryotic cells, catalyzes the removal of intact asparagine-linked oligosaccharide chains from glycoproteins and/or glycopeptides. Since its discovery in 1984, PNGase F has remained as the sole prokaryotic PNGase. Recently, a novel gene encoding a protein with a predicted PNGase domain was identified from a clinical isolate of Elizabethkingia meningoseptica. In this study, the candidate protein was expressed in vitro and was subjected to biochemical and structural analyses. The results revealed that it possesses PNGase activity and has substrate specificity different from that of PNGase F. The crystal structure of the protein was determined at 1.9 Å resolution. Structural comparison with PNGase F revealed a relatively larger glycan-binding groove in the catalytic domain and an additional bowl-like domain with unknown function at the N terminus of the candidate protein. These structural and functional analyses indicated that the candidate protein is a novel prokaryotic N-glycosidase. The protein has been named PNGase F-II.
N - 糖苷酶（PNGase）F是在原核细胞中发现的首个PNGase，它催化从糖蛋白和/或糖肽中去除完整的天冬酰胺连接的寡糖链。自1984年被发现以来，PNGase F一直是唯一的原核PNGase。最近，从脑膜败血伊丽莎白金菌的临床分离株中鉴定出一个编码具有预测PNGase结构域蛋白的新基因。在本研究中，该候选蛋白在体外表达，并进行了生化和结构分析。结果表明它具有PNGase活性，且底物特异性与PNGase F不同。该蛋白的晶体结构在1.9 Å分辨率下测定。与PNGase F的结构比较显示，催化结构域中有一个相对较大的聚糖结合槽，且候选蛋白N端有一个功能未知的额外碗状结构域。这些结构和功能分析表明，该候选蛋白是一种新型原核N - 糖苷酶。该蛋白已被命名为PNGase F-II。
