Heterologous expression and biochemical characterization of a novel multifunctional endo-β-1,4- glucanase (Cel12A) exhibiting transglycosylation and weak cellobiohydrolase activities from the medicinal mushroom Inonotus obliquus

A novel endo-β-1,4-glucanase (Cel12A) from glycoside hydrolase family 12 of Inonotus obliquus was successfully heterologously expressed and biochemical characterized. The gene sequence of endo-β-1,4-glucanase (Cel12A) contains an open reading frame of 729 bp, encoding a protein of 242 amino acid residues with a putative signal peptide residing at the first 16 amino acid residues of the N-terminus of the protein. Recombinant endo-β-1,4-glucanase (Cel12A) exhibited maximum activity at pH 4.5 and 45°C. Notably, the enzyme exhibits psychrophilic traits and remains more than 70% relative activity at 20 ℃. The enzyme displayed strict substrate specificity hydrolyzing (1,4)-β-linkages in glucan and showing a preference for the β-1,4 linkages existed in β-1,3 − 1,4-glucans. Biochemical analysis demonstrated that endo-β-1,4-glucanase (Cel12A) is a multifunctional endo-β-1,4-glucanase (Cel12A) with transglycosylation and weak cellobiohydrolase activities. These diversity of properties makes the enzyme an appropriate candidate for some special applications in the industry.