Bacterial aspartic proteinases

Regions of genomic DNA encoding putative aspartic proteinase domains were amplified by PCR from the bacterial species, Escherichia coli and Haemophilus influenzae. Expression of each of these DNA fragments resulted in the accumulation of the corresponding recombinant proteins in insoluble aggregates, Each recombinant protein was solubilised, refolded and shown to be able to cleave synthetic peptides that have been extensively used previously as substrates for aspartic proteinases of vertebrate, fungal and retroviral origin, Each activity was completely blocked by the diagnostic aspartic proteinase inhibitor, acetyl-pepstatin, This is thus the first report demonstrating unequivocally that aspartic proteinases may be present in bacteria. (C) 1997 Federation of European Biochemical Societies.