title: Substrate binding to a GH131 β-glucanase catalytic domain from Podospora anserina.
abstract: β-Glucanases have been utilized widely in industry to treat various carbohydrate-containing materials. Recently, the Podospora anserina β-glucanase 131A (PaGluc131A) was identified and classified to a new glycoside hydrolases GH131 family. It shows exo-β-1,3/exo-β-1,6 and endo-β-1,4 glucanase activities with a broad substrate specificity for laminarin, curdlan, pachyman, lichenan, pustulan, and cellulosic derivatives. Here we report the crystal structures of the PaGluc131A catalytic domain with or without ligand (cellotriose) at 1.8Å resolution. The cellotriose was clearly observed to occupy the +1 to +3 subsites in substrate binding cleft. The broadened substrate binding groove may explain the diverse substrate specificity. Based on our crystal structures, the GH131 family enzyme is likely to carry out the hydrolysis through an inverting catalytic mechanism, in which E99 and E139 are supposed to serve as the general base and general acid.
authors.affiliation: Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Jiang
authors.forename: Hsiu-Chien
authors.initials: HC
authors.lastname: Chan
authors.forename: Chun-Hsiang
authors.initials: CH
authors.lastname: Huang
authors.forename: Tzu-Ping
authors.initials: TP
authors.lastname: Ko
authors.forename: Ting-Yung
authors.initials: TY
authors.lastname: Huang
authors.forename: Je-Ruei
authors.initials: JR
authors.lastname: Liu
authors.forename: Rey-Ting
authors.initials: RT
authors.lastname: Guo
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D002480:Cellulase / Q000737:chemistry* / Q000648:ultrastructure*; D002482:Cellulose / Q000737:chemistry*; D003198:Computer Simulation; D004789:Enzyme Activation; D008956:Models, Chemical; D008958:Models, Molecular; D048468:Podospora / Q000201:enzymology*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity
chemical_list: D002482:Cellulose; D002480:Cellulase
keywords: Crystal structure; GH131; Glycoside hydrolase; β-Glucanase