Discovery and biochemical characterization of a mannose phosphorylase catalyzing the synthesis of novel β-1,3-mannosides.

Background Mannoside phosphorylases are frequently found in bacteria and play an important role in carbohydrate processing. These enzymes catalyze the reversible conversion of β-1,2- or β-1,4-mannosides to mannose and mannose-1-phosphate in the presence of inorganic phosphate. Methods The biochemical parameters of this recombinantly expressed novel mannose phosphorylase were obtained. Furthermore purified reaction products were subjected to ESI- and MALDI-TOF mass spectrometry and detailed NMR analysis to verify this novel type of β-1,3-mannose linkage. Results We describe the first example of a phosphorylase specifically targeting β-1,3-mannoside linkages. In addition to mannose, this phosphorylase originating from the bacterium Zobellia galactanivorans could add β-1,3-linked mannose to various other monosaccharides and anomerically modified 5-bromo-4-chloro-3-indolyl-glycosides (X-sugars). Conclusions An unique bacterial phosphorylase specifically targeting β-1,3-mannoside linkages was discovered. General significance Functional extension of glycoside hydrolase family 130. [ABSTRACT FROM AUTHOR]