Artificial Fusions between P450 BM3 and an Alcohol Dehydrogenase for Efficient (+)-Nootkatone Production

Multi-enzyme cascades enable the production of valuable chemical compounds, and fusion of the enzymes that catalyze these reactions can improve the reaction outcome. In this work, P450 BM3 from Bacillus megaterium and an alcohol dehydrogenase from Sphingomonas yanoikuyae were fused to bifunctional constructs to enable cofactor regeneration and improve the in vitro two-step oxidation of (+)-valencene to (+)-nootkatone. An up to 1.5-fold increased activity of P450 BM3 was achieved with the fusion constructs compared to the individual enzyme. Conversion of (+)-valencene coupled to cofactor regeneration and performed in the presence of the solubilizing agent cyclodextrin resulted in up to 1080 mg L^-1 (+)-nootkatone produced by the fusion constructs as opposed to 620 mg L^-1 produced by a mixture of the separate enzymes. Thus, a two-step (+)-valencene oxidation was considerably improved through the simple method of enzyme fusion.