title: Xyloglucan breakdown by endo-xyloglucanase family 74 from Aspergillus fumigatus.
abstract: Xyloglucan is the most abundant hemicellulose in primary walls of spermatophytes except for grasses. Xyloglucan-degrading enzymes are important in lignocellulosic biomass hydrolysis because they remove xyloglucan, which is abundant in monocot-derived biomass. Fungal genomes encode numerous xyloglucanase genes, belonging to at least six glycoside hydrolase (GH) families. GH74 endo-xyloglucanases cleave xyloglucan backbones with unsubstituted glucose at the -1 subsite or prefer xylosyl-substituted residues in the -1 subsite. In this work, 137 GH74-related genes were detected by examining 293 Eurotiomycete genomes and Ascomycete fungi contained one or no GH74 xyloglucanase gene per genome. Another interesting feature is that the triad of tryptophan residues along the catalytic cleft was found to be widely conserved among Ascomycetes. The GH74 from Aspergillus fumigatus (AfXEG74) was chosen as an example to conduct comprehensive biochemical studies to determine the catalytic mechanism. AfXEG74 has no CBM and cleaves the xyloglucan backbone between the unsubstituted glucose and xylose-substituted glucose at specific positions, along the XX motif when linked to regions deprived of galactosyl branches. It resembles an endo-processive activity, which after initial random hydrolysis releases xyloglucan-oligosaccharides as major reaction products. This work provides insights on phylogenetic diversity and catalytic mechanism of GH74 xyloglucanases from Ascomycete fungi.
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil.|Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: André Ricardo de Lima
authors.initials: AR
authors.lastname: Damasio
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil.|Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Marcelo Ventura
authors.initials: MV
authors.lastname: Rubio
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil.|Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas, Campinas, SP, Brazil.
authors.forename: Thiago Augusto
authors.initials: TA
authors.lastname: Gonçalves
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil.
authors.forename: Gabriela Felix
authors.initials: GF
authors.lastname: Persinoti
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil.|Departamento de Biotecnologia, Escola de Engenharia de Lorena (EEL), Universidade de São Paulo (USP), Lorena, SP, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Segato
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
authors.forename: Rolf Alexander
authors.initials: RA
authors.lastname: Prade
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil.
authors.forename: Fabiano Jares
authors.initials: FJ
authors.lastname: Contesini
authors.affiliation: Laboratório de Fisiologia e Ecologia de Plantas (LAFIECO), Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo (USP), São Paulo, SP, Brazil.
authors.forename: Amanda Pereira
authors.initials: AP
authors.lastname: de Souza
authors.affiliation: Laboratório de Fisiologia e Ecologia de Plantas (LAFIECO), Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo (USP), São Paulo, SP, Brazil.
authors.forename: Marcos Silveira
authors.initials: MS
authors.lastname: Buckeridge
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, SP, Brazil. fabio.squina@bioetanol.org.br.
authors.forename: Fabio Marcio
authors.initials: FM
authors.lastname: Squina
mesh_terms: D001203:Ascomycota / Q000201:enzymology / Q000235:genetics; D001232:Aspergillus fumigatus / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain / Q000235:genetics; D016681:Genome, Fungal; D005936:Glucans / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D006868:Hydrolysis; D010802:Phylogeny; D013379:Substrate Specificity; D014990:Xylans / Q000378:metabolism*
chemical_list: D005936:Glucans; D006027:Glycosides; D014990:Xylans; C029353:xyloglucan; D006026:Glycoside Hydrolases; C072818:xyloglucan endo(1-4)-beta-D-glucanase
keywords: Aspergillus; Endo-processive; Fungal glucanases; Xyloglucan specific; Xyloglucanases