title: Molecular characterization of a family 5 glycoside hydrolase suggests an induced-fit enzymatic mechanism.
abstract: Glycoside hydrolases (GHs) play fundamental roles in the decomposition of lignocellulosic biomaterials. Here, we report the full-length structure of a cellulase from Bacillus licheniformis (BlCel5B), a member of the GH5 subfamily 4 that is entirely dependent on its two ancillary modules (Ig-like module and CBM46) for catalytic activity. Using X-ray crystallography, small-angle X-ray scattering and molecular dynamics simulations, we propose that the C-terminal CBM46 caps the distal N-terminal catalytic domain (CD) to establish a fully functional active site via a combination of large-scale multidomain conformational selection and induced-fit mechanisms. The Ig-like module is pivoting the packing and unpacking motions of CBM46 relative to CD in the assembly of the binding subsite. This is the first example of a multidomain GH relying on large amplitude motions of the CBM46 for assembly of the catalytically competent form of the enzyme.
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590 São Paulo, Brazil.
authors.forename: Marcelo V
authors.initials: MV
authors.lastname: Liberato
authors.affiliation: Institute of Chemistry, University of Campinas, Campinas 13084-862, São Paulo, Brazil.
authors.forename: Rodrigo L
authors.initials: RL
authors.lastname: Silveira
authors.affiliation: Institute of Chemistry, University of Campinas, Campinas 13084-862, São Paulo, Brazil.
authors.forename: Érica T
authors.initials: ÉT
authors.lastname: Prates
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590 São Paulo, Brazil.
authors.forename: Evandro A
authors.initials: EA
authors.lastname: de Araujo
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590 São Paulo, Brazil.
authors.forename: Vanessa O A
authors.initials: VO
authors.lastname: Pellegrini
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590 São Paulo, Brazil.
authors.forename: Cesar M
authors.initials: CM
authors.lastname: Camilo
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590 São Paulo, Brazil.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Kadowaki
authors.affiliation: Institute of Bioscience, State University of São Paulo, Botucatu 18618-970, São Paulo, Brazil.
authors.forename: Mario de O
authors.initials: Mde O
authors.lastname: Neto
authors.affiliation: European Synchrotron Radiation Facility, Grenoble CS40220, France.
authors.forename: Alexander
authors.initials: A
authors.lastname: Popov
authors.affiliation: Institute of Chemistry, University of Campinas, Campinas 13084-862, São Paulo, Brazil.
authors.forename: Munir S
authors.initials: MS
authors.lastname: Skaf
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590 São Paulo, Brazil.
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
mesh_terms: D000595:Amino Acid Sequence; D000069976:Bacillus licheniformis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D020134:Catalytic Domain; D002482:Cellulose / Q000031:analogs & derivatives / Q000378:metabolism; D016384:Consensus Sequence; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D009038:Motion; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D011487:Protein Conformation; D000072417:Protein Domains; D011994:Recombinant Proteins / Q000737:chemistry; D053838:Scattering, Small Angle; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013780:Tetroses / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D013780:Tetroses; C048468:cellotetraose; D002482:Cellulose