Dye-decolorizing peroxidase (DypA) from the bioleaching acidophilic bacterium Leptospirillum ferriphilum DSM 14647

Leptospirillum ferriphilum is an acidophilic iron-oxidizing bacterium that is relevant in chemical leaching of sulfide ores. In the extremely acidic conditions found in bioleaching operations, this microorganism has to deal with an abundant supply of soluble iron and other metals which might induce oxidative damage to biomolecules through the generation of reactive oxygen species (ROS).

We evaluate the role of dye-decolorizing peroxidase in protection against oxidative stress in L. ferriphilum DSM14647. The genetic region containing dypA gene of this bacterium was cloned and sequenced. The gene has a length of 888 bp and encodes a DypA enzyme of 295 amino acids with an estimated molecular mass of 32.9 kDa. The deduced amino acid sequence revealed that motif involved peroxide reduction activity is highly conserved. Interestingly, dypA gene is localized contiguously to a prx gene that encode for a peroxiredoxin which is involved in organic peroxide reduction. RT-PCR experiments revealed that dypA and prx genes are co-transcribed.  To evaluate the role of DypA in oxidative protection a genetic complementation assay was carried in Escherichia coli cells deficient in catalases/peroxidases. The obtained results indicated that expression of dypA gene restored H₂O₂ resistance to levels exhibited by the wild type strain. Finally, upon exposure of L. ferriphilum to different ROS-generating compounds, significantly transcriptional activation of the dypA gene was observed suggesting an involvement in oxidative stress response in this bacterium.

Dyp is the first dye-decolorizing peroxidase characterized from an acidophilic microorganism, making it a potential candidate for research in basic and applied biology.