Improving the Catalytic Efficiency of <em>Aspergillus fumigatus</em> Glucoamylase toward Raw Starch by Engineering Its N-Glycosylation Sites and Saturation Mutation

J Agric Food Chem. 2022 Sep 25. doi: 10.1021/acs.jafc.2c04733. Online ahead of print.


Raw starch glucoamylase (RSGA) can degrade the raw starch below the starch gelatinization temperature. In this study, to improve the catalytic activity of raw corn starch, N-glycosylation was introduced into the RSGA from Aspergillus fumigatus through site-directed mutation and the recombinant expression in Komagataella phaffii. Among them, the mutants G101S (N99-L100-S101) and Q113T (N111-S112-T113) increased the specific activity of raw corn starch by 1.19- and 1.21-fold, respectively. The optimal temperature of Q113T decreased from 70 to 60 °C. Notably, the combined mutant G101S/Q113T increased the specific activity toward raw starch by 1.22-fold and reduced the optimal temperature from 70 to 60 °C. Moreover, the mutant Q113M with a 1.5-fold increase in the catalytic activity was obtained via saturation mutation at site 113. Thus, the N-glycosylation site engineering is an efficient method to improve the activity of RSGA toward raw starch.

PMID:36154122 | DOI:10.1021/acs.jafc.2c04733

Source: Industry