Protein engineering of GH11 xylanase from Aspergillus fumigatus RT-1 for catalytic efficiency improvement on kenaf biomass hydrolysis

Publication date: Available online 17 July 2019Source: Enzyme and Microbial TechnologyAuthor(s): Siti Intan Rosdianah Damis, Abdul Munir Abdul Murad, Farah Diba Abu Bakar, Siti Aishah Rashid, Nardiah Rizwana Jaafar, Rosli Md. IlliasAbstractEnzyme hydrolysis faces a bottleneck due to the recalcitrance of the lignocellulose biomass. The protein engineering of GH11 xylanase from Aspergillus fumigatus RT-1 was performed near the active site and at the N-terminal region to improve its catalytic efficiency towards pretreated kenaf (Hibiscus cannabinus) hydrolysis. Five mutants were constructed by combined approaches of error-prone PCR, site-saturation and site-directed mutagenesis. The double mutant c168 t/Q192H showed the most effective hydrolysis reaction with a 13.9-fold increase in catalytic efficiency, followed by mutants Y7L and c168 t/Q192 H/Y7L with a 1.6-fold increase, respectively. The enhanced catalytic efficiency evoked an increase in sugar yield of up to 28 % from pretreated kenaf. In addition, mutant c168 t/Q192 H/Y7L improved the thermostability at higher temperature and acid stability. This finding shows that mutations at distances less than 15 Å from the active site and at putative secondary binding sites affect xylanase catalytic efficiency towards insoluble substrates hydrolysis.
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research