title: Xylan-specific carbohydrate-binding module belonging to family 6 enhances the catalytic performance of a GH11 endo-xylanase.
abstract: Xylanases catalyze the hydrolysis of β-1,4-linked xylosyl moieties from xylan chains, one of the most abundant hemicellulosic polysaccharides found in plant cell walls. These enzymes can exist either as single catalytic domains or as modular proteins composed of one or more carbohydrate-binding modules (CBMs) appended to the catalytic core. However, the molecular mechanisms governing the synergistic effects between catalytic domains and their CBMs are not fully understood. Thus, the goal of this study was to evaluate the functional effects of the fusion of a CBM belonging to family 6, which exhibits high affinity to xylan, with the GH11 xylanase from Bacillus subtilis, which does not have a CBM in its wild-type form. The wild-type enzyme (BsXyl11) and the chimeric protein (BsXyl11-CBM6) were heterologously produced in Escherichia coli and purified to homogeneity for biochemical characterization. The molecular fusion did not alter the pH and temperature dependence, but kinetic data revealed an increase of 65% in the catalytic efficiency of the chimeric enzyme. Furthermore, the BsXyl11-CBM6 chimera was used to supplement the commercial cocktail Accellerase® 1500 and improved the reducing sugar release by 17% from pretreated sugarcane bagasse. These results indicate that CBM6 can be used as a molecular tool to enhance the catalytic performance of endo-xylanases (GH11) and provide a new strategy for the development of optimized biocatalysts for biotechnological applications.
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Zaira B
authors.initials: ZB
authors.lastname: Hoffmam
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Letícia M
authors.initials: LM
authors.lastname: Zanphorlin
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Junio
authors.initials: J
authors.lastname: Cota
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: José A
authors.initials: JA
authors.lastname: Diogo
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Gabriela B
authors.initials: GB
authors.lastname: Almeida
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: André R L
authors.initials: AR
authors.lastname: Damásio
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Fabio
authors.initials: F
authors.lastname: Squina
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Mario T
authors.initials: MT
authors.lastname: Murakami
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil. Electronic address: roberto.ruller@bioetanol.org.br.
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruller
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001709:Biotechnology; D002384:Catalysis; D020134:Catalytic Domain; D002482:Cellulose; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007700:Kinetics; D000072417:Protein Domains; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D031786:Saccharum; D013379:Substrate Specificity; D014990:Xylans / Q000737:chemistry / Q000378:metabolism*
chemical_list: D011993:Recombinant Fusion Proteins; D014990:Xylans; D002482:Cellulose; C027433:bagasse; D043364:Endo-1,4-beta Xylanases