Characterization of a Novel β-L-Arabinofuranosidase in Bifidobacterium longum FUNCTIONAL ELUCIDATION OF A DUF1680 FAMILY MEMBER

Pfam DUF1680( PF07944) is an uncharacterized protein family conserved in many species of bacteria, actinomycetes, fungi, and plants. In a previous article, we cloned and characterized the hypBA2 gene as a beta-L-arabinobiosidase in Bifidobacterium longum JCM 1217. In this study, we cloned a DUF1680 family member, the hypBA1 gene, which constitutes a gene cluster with hypBA2. HypBA1 is a novel beta-L-arabinofuranosidase that liberates L-arabinose from the L-arabinofuranose(Araf)-beta 1,2-Araf disaccharide. HypBA1 also transglycosylates 1-alkanols with retention of the anomeric configuration. Mutagenesis and azide rescue experiments indicated that Glu-366 is a critical residue for catalytic activity. This report provides the first characterization of a DUF1680 family member, which defines a new family of glycoside hydrolases, the GH family 127.