Engineering the product profile of a polysialyltransferase

Nat Chem Biol. 2014 Jun;10(6):437-42. doi: 10.1038/nchembio.1501. Epub 2014 Apr 13.


Oligo- and polysaccharides have myriad applications as therapeutic reagents from glycoconjugate vaccines to matrices for tissue engineering. Polysaccharide length may vary over several orders of magnitude and is a critical determinant of both their physical properties and biological activities. Therefore, the tailored synthesis of oligo- and polysaccharides of defined size is a major goal for glycoengineering. By mutagenesis and screening of a bacterial polysialyltransferase (polyST), we identified a single-residue switch that controls the size distribution of polymeric products. Specific substitutions at this site yielded distributive enzymes that synthesize polysaccharides with narrow size distribution ideal for glycoengineering applications. Mechanistic investigation revealed that the wild-type enzyme has an extended binding site that accommodates at least 20 residues of the growing polymer; changes in affinity along this binding site allow fine-tuning of the enzyme's product distribution.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Substitution
  • Binding Sites
  • Chromatography, High Pressure Liquid
  • Escherichia coli / genetics
  • Genes, Synthetic
  • Genetic Drift
  • Kinetics
  • Mutagenesis, Site-Directed
  • Neisseria meningitidis, Serogroup B / enzymology*
  • Polysaccharides, Bacterial / biosynthesis
  • Polysaccharides, Bacterial / chemistry
  • Protein Engineering*
  • Sialic Acids / chemistry
  • Sialyltransferases / chemistry*
  • Sialyltransferases / genetics*


  • Polysaccharides, Bacterial
  • Sialic Acids
  • polysialic acid
  • Sialyltransferases