Discovery of cellobionic acid phosphorylase in cellulolytic bacteria and fungi

Abstract

A novel phosphorylase was characterized as new member of glycoside hydrolase family 94 from the cellulolytic bacterium Xanthomonas campestris and the fungus Neurospora crassa. The enzyme catalyzed reversible phosphorolysis of cellobionic acid. We propose 4-O-β-D-glucopyranosyl-D-gluconic acid: phosphate α-D-glucosyltransferase as the systematic name and cellobionic acid phosphorylase as the short names for the novel enzyme. Several cellulolytic fungi of the phylum Ascomycota also possess homologous proteins. We, therefore, suggest that the enzyme plays a crucial role in cellulose degradation where cellobionic acid as oxidized cellulolytic product is converted into α-D-glucose 1-phosphate and D-gluconic acid to enter glycolysis and the pentose phosphate pathway, respectively.

Keywords: Cellobionic acid phosphorylase; GH; Glycoside hydrolase family 94; Neurospora crassa; PAGE; Xanthomonas campestris; glycoside hydrolase family; polyacrylamide-gel electrophoresis; α-d-glucose 1-phosphate; αGlc1P.