Additional Carbohydrate-Binding Modules Enhance the Insoluble Substrate-Hydrolytic Activity of β-1,3-Glucanase from Alkaliphilic Nocardiopsis sp. F96

Abstract

β-1,3-Glucanase (BglF) from Nocardiopsis sp. F96 is composed of only a catalytic domain. To improve the enzymatic properties of BglF, we attempted to construct chimeric enzymes consisting of BglF and some carbohydrate-binding modules, such as the C-terminal additional domain (CAD) and the N-terminal additional domain (NAD) of β-1,3-glucanase H from Bacillus circulans IAM1165 and the chitin-binding domain (ChBD) of chitinase from alkaliphilic Bacillus sp. J813. CAD-fused BglF (BglF-CAD), NAD-fused BglF (NAD-BglF), both NAD- and CAD-fused BglF (NAD-BglF-CAD) and ChBD-fused BglF (BglF-ChBD) were constructed and characterized. The addition of CAD caused increases in binding abilities and hydrolytic activities toward insoluble β-1,3-glucans. As well as BglF-CAD, the binding ability and hydrolytic activity of BglF-ChBD toward pachyman were also increased. The hydrolytic activity of BglF-CAD at pH 9–10 was higher than that of BglF. The relative activities of BglF-CAD and BglF-ChBD at around 50–70 °C were higher than that of BglF.

• β-1,3-glucan
• β-1,3-glucanase
• glycoside hydrolase (GH) family 16
• chimeric enzyme
• carbohydrate-binding module (CBM)