Loop engineering of a thermostable GH10 xylanase to improve low-temperature catalytic performance for better synergistic biomass-degrading abilities

Abstract

Background Xylanase can efficiently hydrolysis of hemicellulose, a barrier to the efficient saccharification of lignocellulose, into xylooligosaccharides and is widely used in the fields of feed, food and biomass utilization. High-temperature xylanase usually has low catalytic activity below 40°C, which limits its applications. Therefore, improving the properties of xylanases to enable synergistic degradation of lignocellulosic biomass with cellulase is of considerable significance in the field of bioconversion of lignocellulosic biomass. Results In this study, a structure-based rational design strategy was applied to enhance the low-temperature catalytic performance of XYL10C_∆N (WT). Screening and comparison were performed amoung the WT and mutants. In comparison with WT, MF53/53SL + N207G exhibited higher specific activity (2.9-fold; 2090 vs. 710 U/mg) and catalytic efficiency (2.8-fold; 1530 vs. 550 mL/s·mg) at 40°C, as well as higher thermostability (with Tm and T50 increased by 7.7°C and 3.5°C, respectively). Meanwhile, comparing with cellulase-only treatment, the combination of MF53/53SL + N207G and cellulase increased the reducing sugar by 1.6-, 1.2-, and 1.4-folds for degradating corn stalk, wheat bran, and corn cob, with the highest degree of synergy of 1.9, 1.2, and 1.6, respectively. Conclusions This study provided a successful strategy to improve the catalytic properties of enzymes and identified loop2 is a key functional area that affects the low-temperature catalytic efficiency of GH10 xylanase. Several xylanase candidates for applications in feed and bioenergy applications were obtained. Synergistic degradation experiments elucidated a possible mechanism of cellulase inhibition by xylan during the hydrolysis of different types of biomass.

Thermostable enzyme research advances: a bibliometric analysis

“…The most recent research paper on biosensor fluorescent detection of organophosphate pesticides using the thermostable enzyme esterase-2 from Alicyclobacillus acidocaldarius (EST2) with a lipase-like Ser-His-Asp catalytic triad was published in 2022, and is a promising candidate as a bioreceptor for the development of biosensor [62]. Huiying Luo, a researcher at the Chinese Academy of Agricultural Sciences in Beijing, China, studies thermostable xylanase and cellulase, which are commonly used to decompose lignocellulosic biomass and have potential applications in the feed and fuel industries [95,96]. This study sheds light on the underlying mechanism and methods of modifying xylanase for commercial use.…”