Analysis of the Glycoside Hydrolase Family 1 from Wild Jujube Reveals Genes Involved in the Degradation of Jujuboside A

Abstract

Jujubosides are the major medicinal ingredients of Ziziphi Spinosae Semen (the seed of wild jujube). To date, a complete understanding of jujuboside’s metabolic pathways has not been attained. This study has systematically identified 35 β-glucosidase genes belonging to the glycoside hydrolase family 1 (GH1) using bioinformatic methods based on the wild jujube genome. The conserved domains and motifs of the 35 putative β-glucosidases, along with the genome locations and exon–intron structures of 35 β-glucosidase genes were revealed. The potential functions of the putative proteins encoded by the 35 β-glucosidase genes are suggested based on their phylogenetic relationships with Arabidopsis homologs. Two wild jujube β-glucosidase genes were heterologously expressed in Escherichia coli, and the recombinant proteins were able to convert jujuboside A (JuA) into jujuboside B (JuB). Since it has been previously reported that JuA catabolites, including JuB and other rare jujubosides, may play crucial roles in the jujuboside’s pharmacological activity, it is suggested that these two proteins can be used to enhance the utilization potential of jujubosides. This study provides new insight into the metabolism of jujubosides in wild jujube. Furthermore, the characterization of β-glucosidase genes is expected to facilitate investigations involving the cultivation and breeding of wild jujube.