Characterization of a proteolytic enzyme derived from a Bacillus strain that effectively degrades prion protein.

Aims: The purpose of this paper was to screen candidate bacterial strains for the production of proteases suitable for application to the degradation of pathogenic forms of prion protein (PrP(Sc)). This paper describes the biochemical characteristics and proteolytic activity of the isolated protease.

Methods And Results: After screening more than 200 bacterial proteases for keratinolytic activity, we identified a Bacillus stain that produced a protease exhibiting high-degradation activity against a scrapie PrP(Sc). Sequence analysis indicated that this serine-protease belonged to the Subtilisin family and had optimum pH and temperature ranges of 9-10 and 60-70 degrees C. Western blotting analysis revealed that the protease was also capable of decomposing bovine spongiform encephalopathy-infected brain homogenate. In addition, the protease was demonstrated to degrade dried PrP(Sc) that had become firmly attached to a plastic surface considerably more effectively than proteinase K or PWD-1, a previously reported keratinase.

Conclusions: These results indicate that the isolated protease exhibited higher activity for PrP(Sc) degradation compared with other proteases examined.

Significance And Impact Of The Study: This protease could be used under moderate conditions for the decontamination of precision instruments that are susceptible to PrP(Sc) contamination.