Expression and activity of heterologous hydroxyisocaproate dehydrogenases in Synechocystis sp. PCC 6803 ΔhoxYH

Exploiting light to drive redox reactions is currently a hot topic since considered as an environmentally friendly source of energy. Consequently, cyanobacteria, which can use e.g., for generating NADPH, are in the focus research. Previously, it has been shown that various heterologous enzymes could be expressed these microorganisms. Here we demonstrated successful inducer-free expression α-keto-acid dehydrogenases (L-HicDH and D-HicDH) from Lactobacillus confusus DSM 20196 paracasei 20008 Synechocystis sp. PCC 6803 ΔhoxYH mutant using replicative plasmids. While L-HicDH showed poor activity limited by amount enzyme, D-HicDH was applied both vivo vitro, transforming selected α-keto acids corresponding optically pure (R)-α-hydroxy (ee >99%) up 53% 90% conversion, respectively.