Engineering of NADPH Supply Boosts Photosynthesis-Driven Biotransformations

Leen Assil-Companioni, Hanna C. Büchsenschütz, Dániel Solymosi, Nina G. Dyczmons-Nowaczyk, Kristin K.F. Bauer, Silvia Wallner, Peter MacHeroux, Yagut Allahverdiyeva, Marc M. Nowaczyk, Robert Kourist*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Light-driven biocatalysis in recombinant cyanobacteria provides highly atom-efficient cofactor regeneration via photosynthesis, thereby remediating constraints associated with sacrificial cosubstrates. However, despite the remarkable specific activities of photobiocatalysts, self-shading at moderate-high cell densities limits efficient space-time-yields of heterologous enzymatic reactions. Moreover, efficient integration of an artificial electron sink into the tightly regulated network of cyanobacterial electron pathways can be highly challenging. Here, we used CC bond reduction of 2-methylmaleimide by the NADPH-dependent ene-reductase YqjM as a model reaction for light-dependent biotransformations. Time-resolved NADPH fluorescence spectroscopy allowed direct monitoring of in-cell YqjM activity and revealed differences in NADPH steady-state levels and oxidation kinetics between different genetic constructs. This effect correlates with specific activities of whole-cells, which demonstrated conversions of >99%. Further channelling of electrons toward heterologous YqjM by inactivation of the flavodiiron proteins (Flv1/Flv3) led to a 2-fold improvement in specific activity at moderate cell densities, thereby elucidating the possibility of accelerating light-driven biotransformations by the removal of natural competing electron sinks. In the best case, an initial product formation rate of 18.3 mmol h-1 L-1 was reached, allowing the complete conversion of a 60 mM substrate solution within 4 h.

Original languageEnglish
Pages (from-to)11864-11877
Number of pages14
JournalACS Catalysis
Issue number20
Publication statusPublished - 16 Oct 2020


  • cyanobacteria
  • electron channeling
  • flavodiiron proteins
  • light-driven biotransformations
  • NADPH fluorescence
  • photocatalysis
  • photosynthesis
  • Synechocystis

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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