Scientific Reports (Dec 2023)

α-1,3-Glucanase from the gram-negative bacterium Flavobacterium sp. EK-14 hydrolyzes fungal cell wall α-1,3-glucan

  • Masaki Takahashi,
  • Shigekazu Yano,
  • Yui Horaguchi,
  • Yuitsu Otsuka,
  • Wasana Suyotha,
  • Koki Makabe,
  • Hiroyuki Konno,
  • Susumu Kokeguchi

DOI
https://doi.org/10.1038/s41598-023-48627-y
Journal volume & issue
Vol. 13, no. 1
pp. 1 – 12

Abstract

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Abstract The glycoside hydrolase (GH) 87 α-1,3-glucanase (Agl-EK14) gene was cloned from the genomic DNA of the gram-negative bacterium Flavobacterium sp. EK14. The gene consisted of 2940 nucleotides and encoded 980 amino acid residues. The deduced amino acid sequence of Agl-EK14 included a signal peptide, a catalytic domain, a first immunoglobulin-like domain, a second immunoglobulin-like domain, a ricin B-like lectin domain, and a carboxyl-terminal domain (CTD) involved in extracellular secretion. Phylogenetic analysis of the catalytic domain of GH87 enzymes suggested that Agl-EK14 is distinct from known clusters, such as clusters composed of α-1,3-glucanases from bacilli and mycodextranases from actinomycetes. Agl-EK14 without the signal peptide and CTD hydrolyzed α-1,3-glucan, and the reaction residues from 1 and 2% substrates were almost negligible after 1440 min reaction. Agl-EK14 hydrolyzed the cell wall preparation of Aspergillus oryzae and released glucose, nigerose, and nigero-triose from the cell wall preparation. After treatment of A. oryzae live mycelia with Agl-EK14 (at least 0.5 nmol/ml), mycelia were no longer stained by red fluorescent protein-fused α-1,3-glucan binding domains of α-1,3-glucanase Agl-KA from Bacillus circulans KA-304. Results suggested that Agl-EK14 can be applied to a fungal cell wall lytic enzyme.