Biochemical and structural analyses of a bacterial endo-beta-1,2-glucanase reveal a new glycoside hydrolase familyAbe, K., Nakajima, M., Yamashita, T., Matsunaga, H., Kamisuki, S., Nihira, T., Takahashi, Y., Sugimoto, N., Miyanaga, A., Nakai, H., Arakawa, T., Fushinobu, S., Taguchi, H.
(2017) J. Biol. Chem. 292: 7487-7506
- PubMed: 28270506
- DOI: 10.1074/jbc.M116.762724
- Primary Citation of Related Structures:
- PubMed Abstract:
β-1,2-Glucan is an extracellular cyclic or linear polysaccharide from Gram-negative bacteria, with important roles in infection and symbiosis. Despite β-1,2-glucan's importance in bacterial persistence and pathogenesis, only a few reports exist on en ...
β-1,2-Glucan is an extracellular cyclic or linear polysaccharide from Gram-negative bacteria, with important roles in infection and symbiosis. Despite β-1,2-glucan's importance in bacterial persistence and pathogenesis, only a few reports exist on enzymes acting on both cyclic and linear β-1,2-glucan. To this end, we purified an endo -β-1,2-glucanase to homogeneity from cell extracts of the environmental species Chitinophaga arvensicola , and an endo -β-1,2-glucanase candidate gene ( Cpin_6279 ) was cloned from the related species Chitinophaga pinensis The Cpin_6279 protein specifically hydrolyzed linear β-1,2-glucan with polymerization degrees of ≥5 and a cyclic counterpart, indicating that Cpin_6279 is an endo -β-1,2-glucananase. Stereochemical analysis demonstrated that the Cpin_6279-catalyzed reaction proceeds via an inverting mechanism. Cpin_6279 exhibited no significant sequence similarity with known glycoside hydrolases (GHs), and thus the enzyme defines a novel GH family, GH144. The crystal structures of the ligand-free and complex forms of Cpin_6279 with glucose (Glc) and sophorotriose (Glc-β-1,2-Glc-β-1,2-Glc) determined up to 1.7 Å revealed that it has a large cavity appropriate for polysaccharide degradation and adopts an (α/α) 6 -fold slightly similar to that of GH family 15 and 8 enzymes. Mutational analysis indicated that some of the highly conserved acidic residues in the active site are important for catalysis, and the Cpin_6279 active-site architecture provided insights into the substrate recognition by the enzyme. The biochemical characterization and crystal structure of this novel GH may enable discovery of other β-1,2-glucanases and represent a critical advance toward elucidating structure-function relationships of GH enzymes.
the Faculty of Agriculture, Iwate University, Iwate 020-8550.,From the Department of Biotechnology, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657.,the School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuoh-ku, Sagamihara 229-8501.,the Faculty of Agriculture, Niigata University, Niigata 950-2181, and.,the Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, firstname.lastname@example.org.,the Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510.,the Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan.