2xfg

Reassembly and co-crystallization of a family 9 processive endoglucanase from separately expressed GH9 and CBM3c modules

spinqualitylabelsall models 2xfg, resolution 1.68Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xfg is a 2 chain structure with sequence from Acetivibrio thermocellus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.679Å Ligands: CA, CL Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function GUNI_ACET2 This enzyme catalyzes the endohydrolysis of 1,4-beta-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans. Principally active against barley beta-glucan. Publication Abstract from PubMed Non-cellulosomal processive endoglucanase 9I (Cel9I) from Clostridium thermocellum is a modular protein, consisting of a family-9 glycoside hydrolase (GH9) catalytic module and two family-3 carbohydrate-binding modules (CBM3c and CBM3b), separated by linker regions. GH9 does not show cellulase activity when expressed without CBM3c and CBM3b and the presence of the CBM3c was previously shown to be essential for endoglucanase activity. Physical reassociation of independently expressed GH9 and CBM3c modules (containing linker sequences) restored 60-70% of the intact Cel9I endocellulase activity. However, the mechanism responsible for recovery of activity remained unclear. In this work we independently expressed recombinant GH9 and CBM3c with and without their interconnecting linker in Escherichia coli. We crystallized and determined the molecular structure of the GH9/linker-CBM3c heterodimer at a resolution of 1.68 A to understand the functional and structural importance of the mutual spatial orientation of the modules and the role of the interconnecting linker during their re-association. Enzyme activity assays and isothermal titration calorimetry were performed to study and compare the effect of the linker on the re-association. The results indicated that reassembly of the modules could also occur without the linker, albeit with only very low recovery of endoglucanase activity. We propose that the linker regions in the GH9/CBM3c endoglucanases are important for spatial organization and fixation of the modules into functional enzymes. Reassembly and co-crystallization of a family 9 processive endoglucanase from its component parts: structural and functional significance of the intermodular linker.,Petkun S, Rozman Grinberg I, Lamed R, Jindou S, Burstein T, Yaniv O, Shoham Y, Shimon LJ, Bayer EA, Frolow F PeerJ. 2015 Sep 15;3:e1126. doi: 10.7717/peerj.1126. eCollection 2015. PMID:26401442 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glucanase 3D structures

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