A novel fungal metal-dependent α-l-arabinofuranosidase of family 54 glycoside hydrolase shows expanded substrate specificity

Abstract

Trichoderma genus fungi present great potential for the production of carbohydrate-active enzymes (CAZYmes), including glycoside hydrolase (GH) family members. From a renewability perspective, CAZYmes can be biotechnologically exploited to convert plant biomass into free sugars for the production of advanced biofuels and other high-value chemicals. GH54 is an attractive enzyme family for biotechnological applications because many GH54 enzymes are bifunctional. Thus, GH54 enzymes are interesting targets in the search for new enzymes for use in industrial processes such as plant biomass conversion. Herein, a novel metal-dependent GH54 arabinofuranosidase (ThABF) from the cellulolytic fungus Trichoderma harzianum was identified and biochemically characterized. Initial in silico searches were performed to identify the GH54 sequence. Next, the gene was cloned and heterologously overexpressed in Escherichia coli. The recombinant protein was purified, and the enzyme’s biochemical and biophysical properties were assessed. GH54 members show wide functional diversity and specifically remove plant cell substitutions including arabinose and galactose in the presence of a metallic cofactor. Plant cell wall substitution has a major impact on lignocellulosic substrate conversion into high-value chemicals. These results expand the known functional diversity of the GH54 family, showing the potential of a novel arabinofuranosidase for plant biomass degradation.

Whole-Genome Sequencing and Comparative Genomic Analysis of Potential Biotechnological Strains of Trichoderma harzianum, Trichoderma atroviride, andTrichoderma reesei

“…Within the genus Trichoderma, T. harzianum has been used as a commercial biocontrol agent against plant diseases (Fraceto et al, 2018). In addition to their mycoparasitic activities, hydrolytic enzymes from T. harzianum strains have demonstrated great potential in the conversion of lignocellulosic biomass into fermentable sugars (Almeida et al, 2021; Delabona et al, 2020b; Motta et al, 2021; Zhang et al, 2020b). Recently, different types of enzymatic profiles across Trichoderma species were reported, in which Th3844 and Th0179 presented a higher hydrolytic potential during growth on cellulose than that of Ta0020 (Almeida et al, 2021); furthermore, differences between Th3844 and Th0179 concerning the transcriptional regulation coordinated by XYR1 and CRE1 during cellulose degradation were reported (Rosolen et al, 2021).…”

“…In addition to enzymatic activities, the capacity of biocontrol against plant pathogenic fungi has been widely explored in Trichoderma harzianum and Trichoderma atroviride (Medeiros et al, 2017; Saravanakumar et al, 2017). Recently, T. harzianum strains were explored for their enzymatic potential and were demonstrated to be useful for improving the lignocellulosic conversion into sugars during second-generation ethanol (2G ethanol) production (Almeida et al, 2021; Delabona et al, 2020a; Motta et al, 2021; Zhang et al, 2020a).…”