Characterization and crystal structure determination of β-1,2-mannobiose phosphorylase from Listeria innocua.

Glycoside hydrolase family 130 consists of phosphorylases and hydrolases for β-mannosides. Here, we characterized β-1,2-mannobiose phosphorylase from Listeria innocua (Lin0857) and determined its crystal structures complexed with β-1,2-linked mannooligosaccharides. β-1,2-Mannotriose was bound in a U-shape, interacting with a phosphate analog at both ends. Lin0857 has a unique dimer structure connected by a loop, and a significant open-close loop displacement was observed for substrate entry. A long loop, which is exclusively present in Lin0857, covers the active site to limit the pocket size. A structural basis for substrate recognition and phosphorolysis was provided.