Characterization of a novel AA3_1 xylooligosaccharide dehydrogenase from Thermothelomyces myriococcoides CBS 398.93

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Biotechnology for Biofuels and Bioproducts, Volume 15, issue 1
Background: The Carbohydrate-Active enZymes (CAZy) auxiliary activity family 3 (AA3) comprises flavin adenine dinucleotide-dependent (FAD) oxidoreductases from the glucose–methanol–choline (GMC) family, which play auxiliary roles in lignocellulose conversion. The AA3 subfamily 1 predominantly consists of cellobiose dehydrogenases (CDHs) that typically comprise a dehydrogenase domain, a cytochrome domain, and a carbohydrate-binding module from family 1 (CBM1). Results: In this work, an AA3_1 gene from T. myriococcoides CBS 398.93 encoding only a GMC dehydrogenase domain was expressed in Aspergillus niger. Like previously characterized CDHs, this enzyme (TmXdhA) predominantly accepts linear saccharides with β-(1 → 4) linkage and targets the hydroxyl on the reducing anomeric carbon. TmXdhA was distinguished, however, by its preferential activity towards xylooligosaccharides over cellooligosaccharides. Amino acid sequence analysis showed that TmXdhA possesses a glutamine at the substrate-binding site rather than a threonine or serine that occupies this position in previously characterized CDHs, and structural models suggest the glutamine in TmXdhA could facilitate binding to pentose sugars. Conclusions: The biochemical analysis of TmXdhA revealed a catalytic preference for xylooligosaccharide substrates. The modeled structure of TmXdhA provides a reference for the screening of oxidoreductases targeting xylooligosaccharides. We anticipate TmXdhA to be a good candidate for the conversion of xylooligosaccharides to added-value chemicals by its exceptional catalytic ability.
Funding Information: This work was conducted with the funding from Academy of Finland for COCOA (Project Codes 308996 and 308997), Novo Nordisk Foundation for BIOSEMBL and Finnish Cultural Foundation. Publisher Copyright: © 2022, The Author(s).
AA3_1, CAZy AA3, Cellobiose dehydrogenase, Thermothelomyces myriococcoides, Xylooligosaccharide dehydrogenase
Other note
Zhao, H, Karppi, J, Nguyen, T T M, Bellemare, A, Tsang, A, Master, E & Tenkanen, M 2022, ' Characterization of a novel AA3_1 xylooligosaccharide dehydrogenase from Thermothelomyces myriococcoides CBS 398.93 ', Biotechnology for Biofuels and Bioproducts, vol. 15, no. 1, 135 .