The Coptotermes gestroi aldo-keto reductase: a multipurpose enzyme for biorefinery applications

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Tramontina, Robson ; Franco Cairo, Joao Paulo L. ; Liberato, Marcelo V. ; Mandelli, Fernanda ; Sousa, Amanda ; Santos, Samantha ; Rabelo, Sarita Candida ; Campos, Bruna ; Ienczak, Jaciane ; Ruller, Roberto ; Damasio, Andre R. L. ; Squina, Fabio Marcio

• Document type: Journal article
• Source: BIOTECHNOLOGY FOR BIOFUELS; v. 10, JAN 3 2017.
• Web of Science Citations: 6

Abstract

Background: In nature, termites can be considered as a model biological system for biofuel research based on their remarkable efficiency for lignocellulosic biomass conversion. Redox enzymes are of interest in second-generation ethanol production because they promote synergic enzymatic activity with classical hydrolases for lignocellulose saccharification and inactivate fermentation inhibitory compounds produced after lignocellulose pretreatment steps. Results: In the present study, the biochemical and structural characteristics of the Coptotermes gestroi aldo-keto reductase (CgAKR-1) were comprehensively investigated. CgAKR-1 displayed major structural differences compared with others AKRs, including the differences in the amino acid composition of the substrate-binding site, providing basis for classification as a founding member of a new AKR subfamily (family AKR1 I). Immunolocalization assays with anti-CgAKR-1 antibodies resulted in strong fluorescence in the salivary gland, proventriculus, and foregut. CgAKR-1 supplementation caused a 32% reduction in phenolic aldehydes, such as furfural, which act as fermentation inhibitors of hemicellulosic hydrolysates, and improved ethanol fermentation by the xylose-fermenting yeast Scheffersomyces stipitis by 45%. We observed synergistic enzymatic interactions between CgAKR-1 and commercial cellulosic cocktail for sugarcane bagasse saccharification, with a maximum synergism degree of 2.17 for sugar release. Our data indicated that additive enzymatic activity could be mediated by reactive oxygen species because CgAKR-1 could produce hydrogen peroxide. Conclusion: In summary, we identified the founding member of an AKRI subfamily with a potential role in the termite digestome. CgAKR-1 was found to be a multipurpose enzyme with potential biotechnological applications. The present work provided a basis for the development and application of integrative and multipurpose enzymes in the bioethanol production chain. (AU)

• FAPESP's process: 08/58037-9 - Library generation for biomass-conversion enzymes from soil metagenome
• Grantee: Fábio Márcio Squina
• Support type: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants
• FAPESP's process: 13/06336-0 - Study of the Molecular Basis of Carbohydrate Binding Modules (CBMs) from Metagenomic Screenings
• Grantee: Bruna Medéia de Campos
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 14/20576-7 - Characterization of auxiliary (redox) enzymes from the termite Coptotermes gestroi that cooperate with glycolytic hydrolases
• Grantee: Robson Tramontina
• Support type: Scholarships in Brazil - Master
• 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 type: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants
• FAPESP's process: 14/04105-4 - Structural and functional characterization of new cellulases, focusing in the relation between catalytic domains and CBMs
• Grantee: Marcelo Vizoná Liberato
• Support type: Scholarships in Brazil - Post-Doctorate