Discovery of two β-1,2-mannoside phosphorylases showing different chain-length specificities from thermoanaerobacter sp. X-514

Abstract

We characterized Teth514-1788 and Teth514-1789, belonging to glycoside hydrolase family 130, from Thermoanaerobacter sp. X-514. These two enzymes catalyzed the synthesis of 1,2-β-oligomannan using β-1,2-mannobiose and Dmannose as the optimal acceptors, respectively, in the presence of the donor α-Dmannose 1-phosphate. Kinetic analysis of the phosphorolytic reaction toward 1,2-boligomannan revealed that these enzymes followed a typical sequential Bi Bi mechanism. The kinetic parameters of the phosphorolysis of 1,2-β-oligomannan indicate that Teth514-1788 and Teth514-1789 prefer 1,2-β-oligomannans containing α DP ≥3 and β-1,2-Man2, respectively. These results indicate that the two enzymes are novel inverting phosphorylases that exhibit distinct chain-length specificities toward 1,2-β-oligomannan. Here, we propose 1,2-βoligomannan: phosphate α-D-mannosyltransferase as the systematic name and 1,2-β-oligomannan phosphorylase as the short name for Teth514-1788 and β-1,2-mannobiose:phosphate α-D-mannosyltransferase as the systematic name and β-1,2-mannobiose phosphorylase as the short name for Teth514-1789.