Unexpected domains in novel proteases
In the diverse microbial world, proteases are many and varied. Growth and differentiation at the heart of cellular regulation at all levels of organisation involve hydrolysing enzymes, hydrolases. Project researchers in GEMINI cast their net in metagenomic libraries for novel enzymes with industrial applications. Partners based at the University of Goettingen in Germany narrowed the search down to hydrolysing proteases. The screening procedure used was based on the enzymes' ability to hydrolyse skimmed milk. Two genes were found that expressed proteases and were designated proA and proB. The structural domains of the proteins were investigated and related to enzyme function as well as compared with other microbial proteins. Both proA and proB showed very unusual domain structures in that a regulatory P-domain present is normally only found in proteins secreted from eukaryotes. For active protease production, a signal sequence, together with the N-terminal, catalytic and alpha-helical domains found within the structure of the protein were all found to be necessary. Both expressed proteases showed high activity and stability at alkaline pH values and at high temperatures. As such, they show excellent potential in applications where conditions are inclement for most enzymes. Their industrial application could be extended to various sectors including the cleaning and detergent industry.