Addition of α-1,3-glucan-binding domains to α-1,3-glucanase Agn1p from　 Schizosaccharomyces pombe enhances hydrolytic activity of insoluble α-1,3-glucan

• Published in: Journal of general and applied microbiology Vol. 70; no. 2; p. 2024.02.001
• Main Authors: Horaguchi, Yui, Konno, Hiroyuki, Makabe, Koki, Takahashi, Masaki, Xu, Fusheng, Yokomichi, Moe, Yano, Shigekazu
• Format: Journal Article
• Language: English
• Published: Japan Applied Microbiology, Molecular and Cellular Biosciences Research Foundation 01.01.2024; Japan Science and Technology Agency
• Subjects: Binding; C-Terminus; Carbohydrates; Catalytic Domain; Chitinase; E coli; Enzymes; fungal cell-wall; GH71 α-1,3-glucanase; Glucan; Glucans - metabolism; Glycosidases; Glycoside hydrolase; Glycoside Hydrolases - chemistry; Glycoside Hydrolases - genetics; Glycoside Hydrolases - metabolism; Glycosides; Growth hormones; Hydrogen-Ion Concentration; Hydrolysis; Protein Binding; Recombinant Fusion Proteins - chemistry; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Schizosaccharomyces - enzymology; Schizosaccharomyces - genetics; Schizosaccharomyces - metabolism; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - chemistry; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - metabolism; Temperature; Thermal stability; Yeast; α-1,3-glucan binding domain; Schizosaccharomyces pombe; α-1,3-glucan binding domain; GH71 α-1,3-glucanase; fungal cell-wall
• ISSN: 0022-1260; 1349-8037
• DOI: 10.2323/jgam.2024.02.001

The glycoside hydrolase (GH) 71 α-1,3-glucanase (Agn1p) from Schizosaccharomyces pombe consists of an N-terminal signal sequence and a catalytic domain. Meanwhile, the GH87 α-1,3-glucanase (Agl-KA) from Bacillus circulans KA-304 consists of an N-terminal signal sequence, a first discoidin domain (DS1), a carbohydrate-binding module family 6 (CBM6), a threonine and proline repeat linker (TP), a second discoidin domain (DS2), an uncharacterized domain, and a catalytic domain. DS1, CBM6, and DS2 exhibit α-1,3-glucan binding activity. This study involved genetically fusing TP, DS1, CBM6, TP, and DS2 to the C-terminus of Agn1p, generating the fusion enzyme Agn1p-DCD. The fusion enzyme was then expressed in Escherichia coli and purified from the cell-free extract. Agn1p-DCD and Agn1p exhibited similar characteristics, such as optimal pH, optimal temperature, pH stability, and thermostability. Insoluble α-1,3-glucan (1%) hydrolyzing assay showed that Agn1p-DCD and Agn1p released approximately 7.6 and 5.0 mM of reducing sugars, respectively, after 48 h of reaction. Kinetic analysis and an α-1,3-glucan binding assay indicated that the addition of DS1, CBM6, and DS2 enhanced the affinity of Agn1p for α-1,3-glucan. Moreover, Agn1p-DCD contributed to enhancing the fungal growth inhibition activity when combined with a mixture of GH19 chitinase and GH16 β-1,3-glucanase.