title: Structural basis for glucose tolerance in GH1 β-glucosidases.
abstract: Product inhibition of β-glucosidases (BGs) by glucose is considered to be a limiting step in enzymatic technologies for plant-biomass saccharification. Remarkably, some β-glucosidases belonging to the GH1 family exhibit unusual properties, being tolerant to, or even stimulated by, high glucose concentrations. However, the structural basis for the glucose tolerance and stimulation of BGs is still elusive. To address this issue, the first crystal structure of a fungal β-glucosidase stimulated by glucose was solved in native and glucose-complexed forms, revealing that the shape and electrostatic properties of the entrance to the active site, including the +2 subsite, determine glucose tolerance. The aromatic Trp168 and the aliphatic Leu173 are conserved in glucose-tolerant GH1 enzymes and contribute to relieving enzyme inhibition by imposing constraints at the +2 subsite that limit the access of glucose to the -1 subsite. The GH1 family β-glucosidases are tenfold to 1000-fold more glucose tolerant than GH3 BGs, and comparative structural analysis shows a clear correlation between active-site accessibility and glucose tolerance. The active site of GH1 BGs is located in a deep and narrow cavity, which is in contrast to the shallow pocket in the GH3 family BGs. These findings shed light on the molecular basis for glucose tolerance and indicate that GH1 BGs are more suitable than GH3 BGs for biotechnological applications involving plant cell-wall saccharification.
authors.affiliation: Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, CP 6192, 13083-970 Campinas-SP, Brazil.
authors.forename: Priscila Oliveira
authors.initials: PO
authors.lastname: de Giuseppe
authors.affiliation: Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, CP 6192, 13083-970 Campinas-SP, Brazil.
authors.forename: Tatiana de Arruda Campos Brasil
authors.initials: Tde A
authors.lastname: Souza
authors.affiliation: Department of Chemistry, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, 14040-901 Ribeirão Preto-SP, Brazil.
authors.forename: Flavio Henrique Moreira
authors.initials: FH
authors.lastname: Souza
authors.affiliation: Department of Organic Chemistry, Institute of Chemistry, State University of Campinas, 13083-970 Campinas-SP, Brazil.
authors.forename: Leticia Maria
authors.initials: LM
authors.lastname: Zanphorlin
authors.affiliation: Department of Chemistry, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, 14040-901 Ribeirão Preto-SP, Brazil.
authors.forename: Carla Botelho
authors.initials: CB
authors.lastname: Machado
authors.affiliation: Department of Chemistry, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, 14040-901 Ribeirão Preto-SP, Brazil.
authors.forename: Richard John
authors.initials: RJ
authors.lastname: Ward
authors.affiliation: Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, 14040-901 Ribeirão Preto-SP, Brazil.
authors.forename: Joao Atilio
authors.initials: JA
authors.lastname: Jorge
authors.affiliation: Department of Chemistry, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, 14040-901 Ribeirão Preto-SP, Brazil.
authors.forename: Rosa dos Prazeres Melo
authors.initials: Rdos P
authors.lastname: Furriel
authors.affiliation: Brazilian Biosciences National Laboratory, National Center for Research in Energy and Materials, CP 6192, 13083-970 Campinas-SP, Brazil.
authors.forename: Mario Tyago
authors.initials: MT
authors.lastname: Murakami
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D044602:Cellulases / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D005947:Glucose / Q000737:chemistry*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D053838:Scattering, Small Angle; D017386:Sequence Homology, Amino Acid
chemical_list: D044602:Cellulases; D005947:Glucose
keywords: glucose tolerance; glycoside hydrolase family 1; β-glucosidase