Xyloglucan breakdown by endo-xyloglucanase family 74 from Aspergillus fumigatus

Author(s)

de Lima Damasio, Andre Ricardo ; Rubio, Marcelo Ventura ; Goncalves, Thiago Augusto ; Persinoti, Gabriela Felix ; Segato, Fernando ; Prade, Rolf Alexander ; Contesini, Fabiano Jares ; de Souza, Amanda Pereira ; Buckeridge, Marcos Silveira ; Squina, Fabio Marcio

• Document type: Journal article
• Source: Applied Microbiology and Biotechnology; v. 101, n. 7, p. 2893-2903, APR 2017.
• Web of Science Citations: 7

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. (AU)

• FAPESP's process: 11/02169-7 - Aspergillus nidulans as a model for heterologous expression of cellulases and hemicellulases
• Grantee: André Ricardo de Lima Damasio
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 08/58037-9 - Library generation for biomass-conversion enzymes from soil metagenome
• Grantee: Fábio Márcio Squina
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants
• FAPESP's process: 12/20549-4 - Secretion of heterologous glycoproteins in Aspergillus: effect of glycosylation pattern in functional parameters of glycosyl hydrolases
• Grantee: André Ricardo de Lima Damasio
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants
• FAPESP's process: 14/18714-2 - Enzymatic oxidation of sugarcane bagasse: discovery, characterization and new application of oxidative enzymes active in carbohydrates, applied to the enhancement of a fungal cell factory
• Grantee: Fernando Segato
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants