title: Catalytic Mechanism of a Novel Glycoside Hydrolase Family 16 "Elongating" β-Transglycosylase.
abstract: Carbohydrates are complex macromolecules in biological metabolism. Enzymatic synthesis of carbohydrates is recognized as a powerful tool to overcome the problems associated with large scale synthesis of carbohydrates. Novel enzymes with significant transglycosylation ability are still in great demand in glycobiology studies. Here we report a novel glycoside hydrolase family 16 "elongating" β-transglycosylase from Paecilomyces thermophila (PtBgt16A), which efficiently catalyzes the synthesis of higher polymeric oligosaccharides using β-1,3/1,4-oligosaccharides as donor/acceptor substrates. Further structural information reveals that PtBgt16A has a binding pocket around the -1 subsite. The catalytic mechanism of PtBgt16A is partly similar to an exo-glycoside hydrolase, which cleaves the substrate from the non-reducing end one by one. However, PtBgt16A releases the reducing end product and uses the remainder glucosyl as a transglycosylation donor. This catalytic mechanism has similarity with the catalytic mode of amylosucrase, which catalyzes the transglycosylation products gradually extend by one glucose unit. PtBgt16A thus has the potential to be a tool enzyme for the enzymatic synthesis of new β-oligosaccharides and glycoconjugates.
authors.affiliation: From the Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China; the School of Biotechnology, State Key Laboratory of Bioreactor Engineering, Research and Development Center of Separation and Extraction Technology in Fermentation Industry, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Qin
authors.affiliation: From the Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Yang
authors.affiliation: the School of Biotechnology, State Key Laboratory of Bioreactor Engineering, Research and Development Center of Separation and Extraction Technology in Fermentation Industry, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Liming
authors.initials: L
authors.lastname: Zhao
authors.affiliation: the Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Xin
authors.initials: X
authors.lastname: You
authors.affiliation: the Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.affiliation: From the Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. Electronic address: zhqjiang@cau.edu.cn.
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D002384:Catalysis; D062610:Fungal Polysaccharides / Q000096:biosynthesis* / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000235:genetics; D010143:Paecilomyces / Q000201:enzymology* / Q000235:genetics; D014166:Transferases / Q000235:genetics / Q000378:metabolism*
chemical_list: D062610:Fungal Polysaccharides; D005656:Fungal Proteins; D009097:Multienzyme Complexes; D009844:Oligosaccharides; C023176:transglycosidase enzyme system; D014166:Transferases; D006026:Glycoside Hydrolases
keywords: enzyme catalysis; enzyme mechanism; enzyme structure; glycoside hydrolase; protein crystallization