Autodisplay of glucose-6-phosphate dehydrogenase for redox cofactor regeneration at the cell surface

Biotechnol Bioeng. 2017 Aug;114(8):1658-1669. doi: 10.1002/bit.26308. Epub 2017 Jun 6.

Abstract

Inherent cofactor regeneration is a pivotal feature of whole cell biocatalysis. For specific biotechnological applications, surface display of enzymes is emerging as a tool to circumvent mass transfer limitations or enzyme stability problems. Even complex reactions can be accomplished applying displayed enzymes. Yet, industrial utilization of the technique is still impeded by lacking cofactor regeneration at the cell surface. Here, we report on the surface display of a glucose-6-phoshate dehydrogenase (G6PDH) via Autodisplay to address this limitation and regenerate NADPH directly at the cell surface. The obtained whole cell biocatalyst demonstrated similar kinetic parameters compared to the purified enzyme, more precisely KM values of 0.2 mM for NADP+ and calculated total turnover numbers of 107 . However, the KM for the substrate G6P increased by a factor of 7 to yield 1.5 mM. The whole cell biocatalyst was cheaper to produce, easy to separate from the reaction mixture and reusable in consecutive reaction cycles. Furthermore, lyophilization allowed storage at room temperature. The whole cell biocatalyst displaying G6PDH was applicable for NADPH regeneration in combination with soluble as well as surface displayed enzymes and model reactions in combination with bacterial CYP102A1 and human CYP1A2 were realized. Biotechnol. Bioeng. 2017;114: 1658-1669. © 2017 Wiley Periodicals, Inc.

Keywords: NADPH; autodisplay; cofactor regeneration; glucose-6-phosphate dehydrogenase; surface display; whole cell biocatalysis.

MeSH terms

  • Cell Membrane / genetics
  • Cell Membrane / metabolism*
  • Coenzymes / genetics
  • Coenzymes / metabolism*
  • Escherichia coli / physiology*
  • Gene Expression Regulation, Enzymologic / genetics
  • Glucosephosphate Dehydrogenase / genetics
  • Glucosephosphate Dehydrogenase / metabolism*
  • NADP / genetics
  • NADP / metabolism*
  • Oxidation-Reduction
  • Protein Engineering / methods*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism

Substances

  • Coenzymes
  • Recombinant Proteins
  • NADP
  • Glucosephosphate Dehydrogenase