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Identification and characterization of thermostable glucose dehydrogenases from thermophilic filamentous fungi

Abstract

FAD-dependent glucose dehydrogenase (FAD-GDH), which contains FAD as a cofactor, catalyzes the oxidation of d-glucose to d-glucono-1,5-lactone, and plays an important role in biosensors measuring blood glucose levels. In order to obtain a novel FAD-GDH gene homolog, we performed degenerate PCR screening of genomic DNAs from 17 species of thermophilic filamentous fungi. Two FAD-GDH gene homologs were identified and cloned from Talaromyces emersonii NBRC 31232 and Thermoascus crustaceus NBRC 9129. We then prepared the recombinant enzymes produced by Escherichia coli and Pichia pastoris. Absorption spectra and enzymatic assays revealed that the resulting enzymes contained oxidized FAD as a cofactor and exhibited glucose dehydrogenase activity. The transition midpoint temperatures (T m) were 66.4 and 62.5 °C for glycosylated FAD-GDHs of T. emersonii and T. crustaceus prepared by using P. pastoris as a host, respectively. Therefore, both FAD-GDHs exhibited high thermostability. In conclusion, we propose that these thermostable FAD-GDHs could be ideal enzymes for use as thermotolerant glucose sensors with high accuracy.

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Correspondence to Kenji Yokoyama.

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The authors declare that they have no competing interests.

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This articles does not contain any studies with human participants or animals performed by any of the authors.

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Kazumichi Ozawa and Hisanori Iwasa contributed equally to this work.

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Ozawa, K., Iwasa, H., Sasaki, N. et al. Identification and characterization of thermostable glucose dehydrogenases from thermophilic filamentous fungi. Appl Microbiol Biotechnol 101, 173–183 (2017). https://doi.org/10.1007/s00253-016-7754-7

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  • DOI: https://doi.org/10.1007/s00253-016-7754-7

Keywords

  • FAD-dependent glucose dehydrogenase
  • Gene cloning
  • Recombinant protein production
  • Thermostability