Development of a simplified purification method for a novel formaldehyde dismutase variant from Pseudomonas putida J3

- A novel formaldehyde dismutase gene was identified in Pseudomonas putida J3.
- High expression levels were obtained in an Escherichia coli rhamnose-inducible system (51 U mg−1).
- Chaperone GroESL coexpression increased yield of activity in raw extracts 8.6 fold.
- First report of a functional formaldehyde dismutase with a C-terminal 6xHis-Tag allowing simple affinity purification.
- Formaldehyde dismutase will be useful for biomethanol production from biogas.

Formaldehyde dismutase (FDM) is a very interesting enzyme, due to the fact that it comprises an internal cofactor regeneration mechanism. The FDM, therefore, is able to catalyze redox reactions independent of exogenous cofactor addition, rendering the enzyme powerful for industrial applications. Currently, only one enzyme of this type has been characterized enzymatically. Furthermore, only one additional DNA-sequence with high homology to FDM has been published. In this work, we identified a new variant of a formaldehyde dismutase gene (fdm) in the Pseudomonas putida J3 strain. To isolate and characterize the enzyme, we developed a simplified method for its purification. This purification is based on a C-terminal 6xHis-tag, which enables functional expression of the enzyme in E. coli and a one-step purification method. In addition, we tested several expression systems for optimal yields and combined this with co-expression of the chaperonins GroESL. Using this simplified and rapid method, we are now able to produce sufficient material in reproducible quality and quantity for application tests with the enzyme. The newly identified enzyme will be applied in a redox cascade for biomethanol production from biogas and shows potential for further industrial biotransformation with integrated cofactor recycling.