XynDZ5: A New Thermostable GH10 Xylanase

Abstract

Xylanolytic enzymes have a broad range of applications in industrial biotechnology as biocatalytic components of various processes and products, such as food additives, bakery products, coffee extraction, agricultural silage and functional foods. An increasing market demand has driven the growing interest for the discovery of xylanases with specific industrially relevant characteristics, such as stability at elevated temperatures and in the presence of other denaturing factors, which will facilitate their incorporation into industrial processes. In this work, we report the discovery and biochemical characterization of a new thermostable GH10 xylanase, termed XynDZ5, exhibiting only 26% amino acid sequence identity to the closest characterized xylanolytic enzyme. This new enzyme was discovered in an Icelandic hot spring enrichment culture of a Thermoanaerobacterium species using a recently developed bioinformatic analysis platform. XynDZ5 was produced recombinantly in Escherichia coli, purified and characterized biochemically. This analysis revealed that it acts as an endo-1,4β-xylanase that performs optimally at 65-75 • C and pH 7.5. The enzyme is capable of retaining high levels of catalytic efficiency after several hours of incubation at high temperatures, as well as in the presence of significant concentrations of a range of metal ions and denaturing agents. Interestingly, the XynDZ5 biochemical profile was found to be atypical, as it also exhibits significant exo-activity. Computational modeling of its three-dimensional structure predicted a (β/α) 8 TIM barrel fold, which is very frequently encountered among family GH10 enzymes. This modeled structure has provided clues about structural features that may explain aspects of its catalytic performance. Our results suggest that XynDZ5 represents a promising new candidate biocatalyst appropriate for several high-temperature biotechnological applications in the pulp, paper, baking, animal-feed and biofuel industries.

Rahnella sp., a Dominant Symbiont of the Core Gut Bacteriome of Dendroctonus Species, Has Metabolic Capacity to Degrade Xylan by Bifunctional Xylanase-Ferulic Acid Esterase

“…In addition, hydrolysis products, xylose, and xylobiose, identified in activity assays indicate that it acts on the ends of the xylan ( Figure 8 ). The identification of xylobiose and xylose suggests that this enzyme has exo -activity, as has been previously observed with the thermostable xylanase of Thermoanarobacterium species ( Zarafeta et al, 2020 ). These substrates derived from xylan hydrolysis are compounds of easy assimilation and can be used by other symbionts present in the intestine and by insects.…”

Expression, Characterization and Its Deinking Potential of a Thermostable Xylanase From Planomicrobium glaciei CHR43

“…According to previous publications, similar xylanases active at elevated temperatures and alkaline pH have ever been reported. For instance, XynDZ5, a newly reported thermostable xylanolytic enzyme derived from Thermoanaerobacterium thermosaccharolyticum , performs best at 65–75°C and pH 7.5 (Zarafeta et al, 2020 ). Another xylanase XynHB originating from B. pumilus HBP8 was extracellular secreted expressed in E. coli , which have showed high activity under alkaline conditions at 70°C (Zhang et al, 2020 ).…”

Aspergillus sydowii: Genome Analysis and Characterization of Two Heterologous Expressed, Non-redundant Xylanases

“…Based on the data available, it can be assumed that for xylanase I, a substrate concentration of 2.5% provides the highest activities, while for xylanase II no possible substrate inhibition was observed in the measured range. Similar behavior could be observed for the heterologous expressed XynDZ5 GH10 xylanase from Thermoanaerobacterium sp., where three different xylan sources were used, showing about 10-fold increase of activity if 30 g/L (3%) was used instead 0.3% ( Zarafeta et al, 2020 ). Substrate affinity of xylanase II 6.71 ± 3.14 g/L was comparable to literature values of 0.7–6.6 g/L ( Li et al, 2006 , 2010 ; Sharma et al, 2010 ; Ding et al, 2018 ; Yadav et al, 2018 ), while xylanase I showed a reduced affinity with a K M of 20.68 ± 8.53 g/L.…”