1998 Volume 123 Issue 1 Pages 94-100
Sialyltransferase 0160, a bacterial sialyltransferase which catalyzes the incorporation of NeuAc from CMP-NeuAc into the galactose residue of the carbohydrate chain at position 6, is produced by Photobacterium damsela JT0160. The gene coding for sialyltransferase 0160 (bst) was cloned, sequenced, and expressed in Escherichia coli. The sialyltransferase 0160 gene contains an open reading frame of 2, 028 base pairs encoding a protein of 675 amino acid residues. The deduced amino acid sequence of sialyltransferase 0160 did not contain the sialylmotif and had no significant similarity to mammalian sialyltransferases. Crude extracts of cultured E. coli MV 1184 cells carrying an expression plasmid for the sialyltransferase 0160 gene showed sialyltransferase activity, which was identified as β-galactoside α2, 6-sialyltransferase activity by enzymatic reaction product analysis. In addition, when mutant genes, lacking 3'-coding regions for COON-terminal portions of the protein, which are thought to form α-helix structures, were expressed in E. coli MV 1184, solubleform enzymes were obtained. This implies that the COON-terminal portion of sialyltransferase 0160 is required for membrane binding.
