A recombinant α-(2→3)-sialyltransferase with an extremely broad acceptor substrate specificity from Photobacterium sp. JT-ISH-224 can transfer N-acetylneuraminic acid to inositols

Efficiency of organic solvents on the ability of α2,3-sialyltransferase from Photobacterium sp. JT-ISH-224 to control a hydrolysis side reaction

Enzymatic synthesis of oligosaccharides using specific sialyltransferases enables single-step glycosylation with high positional and anomeric structural selectivity. The α2,3-sialyltransferase cloned from the marine bacterium Photobacterium sp. JT-ISH-224 has unique and broad acceptor specificity, but this enzyme possesses not only sialyltransferase activity but also sialidase activity. To synthesize sialoside derivative effectively, only sialyltransferase activity is required. We report here that addition of organic solvents was effective to control the sialidase activity and a resulting product was not hydrolyzed. The enzyme was even active in the presence of acetonitrile, ethanol, methanol, or acetone. To determine the suitable concentrations of these organic solvents, only sialyltransferase activity could be allowed, and as a result, the stable synthesis of sialoside could be achieved.

Marine bacterial sialyltransferases

Sialyltransferases transfer N-acetylneuraminic acid (Neu5Ac) from the common donor substrate of these enzymes, cytidine 5′-monophospho-N-acetylneuraminic acid (CMP-Neu5Ac), to acceptor substrates. The enzymatic reaction products including sialyl-glycoproteins, sialyl-glycolipids and sialyl-oligosaccharides are important molecules in various biological and physiological processes, such as cell-cell recognition, cancer metastasis, and virus infection. Thus, sialyltransferases are thought to be important enzymes in the field of glycobiology. To date, many sialyltransferases and the genes encoding them have been obtained from various sources including mammalian, bacterial and viral sources. During the course of our research, we have detected over 20 bacteria that produce sialyltransferases. Many of the bacteria we isolated from marine environments are classified in the genus Photobacterium or the closely related genus Vibrio. The paper reviews the sialyltransferases obtained mainly from marine bacteria.