Biochemical characterization of a novel glucose-tolerant GH3 [beta]-glucosidase

Beta-glucosidase (Bgl) is an enzyme with considerable food, beverage, and biofuel processing potential. However, as many Bgls are inhibited by their reaction end product glucose, their industrial applications are greatly limited. In this study, a novel Bgl gene (Bgl1973) was cloned from Leifsonia sp...

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Veröffentlicht in:Applied microbiology and biotechnology 2022-08, Vol.106 (13-16), p.5063
Hauptverfasser: He, Yi, Wang, Chenxi, Jiao, Ronghu, Ni, Qinxue, Wang, Yan, Gao, Qianxin, Zhang, Youzuo, Xu, Guangzhi
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Sprache:eng
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Zusammenfassung:Beta-glucosidase (Bgl) is an enzyme with considerable food, beverage, and biofuel processing potential. However, as many Bgls are inhibited by their reaction end product glucose, their industrial applications are greatly limited. In this study, a novel Bgl gene (Bgl1973) was cloned from Leifsonia sp. ZF2019 and heterologously expressed in E. coli. Sequence analysis and structure modeling revealed that Bgl1973 was 748 aa, giving it a molecular weight of 78 kDa, and it showed high similarity with the glycoside hydrolase 3 (GH3) family Bgls with which its active site residues were conserved. By using pNPGlc (p-nitrophenyl-[beta]-D-glucopyranoside) as substrate, the optimum temperature and pH of Bgl1973 were shown to be 50 °C and 7.0, respectively. Bgl1973 was insensitive to most metal ions (12.5 mM), 1% urea, and even 0.1% Tween-80. This enzyme maintained 60% of its original activity in the presence of 20% NaCl, demonstrating its excellent salt tolerance. Furthermore, it still had 83% residual activity in 1 M of glucose, displaying its outstanding glucose tolerance. The K.sub.m, V.sub.max, and k.sub.cat of Bgl1973 were 0.22 mM, 44.44 [mu]mol/min mg, and 57.78 s.sup.-1, respectively. Bgl1973 had a high specific activity for pNPGlc (19.10 ± 0.59 U/mg) and salicin (20.43 ± 0.92 U/mg). Furthermore, molecular docking indicated that the glucose binding location and the narrow and deep active channel geometry might contribute to the glucose tolerance of Bgl1973. Our results lay a foundation for the studying of this glucose-tolerant [beta]-glucosidase and its applications in many industrial settings.
ISSN:0175-7598
DOI:10.1007/s00253-022-12064-0