A novel acid-tolerant β-xylanase from Scytalidium candidum 3C for the synthesis of o-nitrophenyl xylooligosaccharides

Elena V. Eneyskaya, Kirill S. Bobrov (Corresponding Author), Maria V. Kashina, Anna S. Borisova, Anna A. Kulminskaya

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Endo-β-xylanases are hemicellulases involved in the conversion of xylans in plant biomass. Here, we report a novel acidophilic β-xylanase (ScXynA) with high transglycosylation abilities that was isolated from the filamentous fungus Scytalidium candidum 3C. ScXynA was identified as a glycoside hydrolase family 10 (GH10) dimeric protein, with a molecular weight of 38 ± 5 kDa per subunit. The enzyme catalyzed the hydrolysis of different xylans under acidic conditions and was stable in the pH range 2.6–4.5. The kinetic parameters of ScXynA were determined in hydrolysis reactions with p-nitrophenyl-β-d-cellobioside (pNP-β-Cel) and p-nitrophenyl-β-d-xylobioside (pNP-β-Xyl2), and kcat/Km was found to be 0.43 ± 0.02 (s·mM)−1 and 57 ± 3 (s·mM)−1, respectively. In the catalysis of the transglycosylation o-nitrophenyl-β-d-xylobioside (oNP-β-Xyl2) acted both as a donor and an acceptor, resulting in the efficient production of o-nitrophenyl xylooligosaccharides, with a degree of polymerization of 3–10 and o-nitrophenyl-β-d-xylotetraose (oNP-β-Xyl4) as the major product (18.5% yield). The modeled ScXynA structure showed a favorable position for ligand entry and o-nitrophenyl group accommodation in the relatively open −3 subsite, while the cleavage site was covered with an extended loop. These structural features provide favorable conditions for transglycosylation with oNP-β-Xyl2. The acidophilic properties and high transglycosylation activity make ScXynA a suitable choice for various biotechnological applications, including the synthesis of valuable xylooligosaccharides.

Original languageEnglish
Pages (from-to)971-982
Number of pages12
JournalJournal of Basic Microbiology
Volume60
Issue number11-12
DOIs
Publication statusPublished - Nov 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • glycoside hydrolase family 10
  • o-nitrophenyl xylooligosaccharides
  • transglycosylation
  • β-xylanase

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