Characterization of a Pyranose Oxidase/C-Glycoside Oxidase from Microbacterium sp. 3H14, Belonging to the Unexplored Clade II of Actinobacterial POx/CGOx.

Pyranose oxidase (POx) is an FAD-dependent oxidoreductase and belongs to the glucose-methanol-choline (GMC) superfamily of oxidoreductases. As recently reported, POxs and FAD-dependent C-glycoside oxidases (CGOxs) share the same sequence space, and phylogenetic analysis of actinobacterial sequences belonging to this shared sequence space showed that it can be divided into four clades. Here, we report the biochemical characterization of a POx/CGOx from Microbacterium sp. 3H14 (MPOx), belonging to the hitherto unexplored clade II of actinobacterial POx/CGOx. Overall, MPOx demonstrates comparable features to POxs/CGOxs of clades III and IV, including the preference for glycosides over monosaccharides as electron donors. However, as MPOx efficiently oxidizes the C-glycoside aspalathin as well as the O-glycoside phlorizin, it shows activity with yet another set of glycoside structures compared to other POx/CGOx members.