Abstact

α-L-Arabinofuranosidases, belonging to the glycoside hydrolase family (GH) 62, hydrolyze the α-1,2- or α-1,3-bond to liberate L-arabinofuranose from the xylan backbone. Here, we determined the structure of the C-terminal catalytic domain of CcAbf62A, a GH62 α-L-arabinofuranosidase from Coprinopsis cinerea. CcAbf62A is composed of a five-bladed β-propeller, as observed in other GH62 enzymes. The structure near the active site of CcAbf62A is also highly homologous to those of other GH62 enzymes. However, a calcium atom in the catalytic center interacts with an asparagine residue, Asn279, which is not found in other GH62 enzymes. In addition, some residues in subsites +3R, +2NR, +3NR, and +4NR of CcAbf62A are not conserved in other GH62 enzymes. In particular, a histidine residue, His221, is uniquely observed in subsite +2NR of CcAbf62A, which is likely to influence the substrate specificity. The results obtained here suggest that the amino acid residues that interact with the xylan backbone vary among the GH62 enzymes, despite the high similarity of their overall structures.