Bioengineering of bacterial polymer inclusions catalyzing the synthesis of N-acetylneuraminic acid

Appl Environ Microbiol. 2013 May;79(9):3116-21. doi: 10.1128/AEM.03947-12. Epub 2013 Mar 1.

Abstract

N-Acetylneuraminic acid is produced by alkaline epimerization of N-acetylglucosamine to N-acetylmannosamine and then subsequent condensation with pyruvate catalyzed by free N-acetylneuraminic acid aldolase. The high-alkaline conditions of this process result in the degradation of reactants and products, while the purification of free enzymes to be used for the synthesis reaction is a costly process. The use of N-acetylglucosamine 2-epimerase has been seen as an alternative to the alkaline epimerization process. In this study, these two enzymes involved in N-acetylneuraminic acid production were immobilized to biopolyester beads in vivo in a one-step, cost-efficient process of production and isolation. Beads with epimerase-only, aldolase-only, and combined epimerase/aldolase activity were recombinantly produced in Escherichia coli. The enzymatic activities were 32 U, 590 U, and 2.2 U/420 U per gram dry bead weight, respectively. Individual beads could convert 18% and 77% of initial GlcNAc and ManNAc, respectively, at high substrate concentrations and near-neutral pH, demonstrating the application of this biobead technology to fine-chemical synthesis. Beads establishing the entire N-acetylneuraminic acid synthesis pathway were able to convert up to 22% of the initial N-acetylglucosamine after a 50-h reaction time into N-acetylneuraminic acid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Biocatalysis
  • Bioengineering
  • Carbohydrate Epimerases / chemistry
  • Carbohydrate Epimerases / genetics
  • Carbohydrate Epimerases / metabolism
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Gene Expression
  • Hexosamines / metabolism
  • Hydrogen-Ion Concentration
  • Microspheres
  • N-Acetylneuraminic Acid / metabolism*
  • Oxo-Acid-Lyases / chemistry
  • Oxo-Acid-Lyases / genetics
  • Oxo-Acid-Lyases / metabolism
  • Polyhydroxyalkanoates / chemistry*
  • Polymers / chemistry*
  • Pyruvic Acid / metabolism
  • Recombinant Fusion Proteins
  • Synechocystis

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Hexosamines
  • Polyhydroxyalkanoates
  • Polymers
  • Recombinant Fusion Proteins
  • Pyruvic Acid
  • Oxo-Acid-Lyases
  • N-acetylneuraminate lyase
  • Carbohydrate Epimerases
  • N-acyl-D-glucosamine 2-epimerase
  • N-Acetylneuraminic Acid
  • N-acetylmannosamine