Characteristics, isolation and role in the infectious process of Pseudomonas aeruginosa protease.

Pseudomonas aeruginosa produces the extracellular enzyme protease, which plays an important role in the development of the infectious process caused by this microorganism. Protease is produced in three types, I, II and III, with protease II being responsible for 75% of the total proteolytic activity of protease. The molecular mass of protease II has been determined by different methods; the values obtained are 23000 and 39500. This discrepancy may be associated with an autodigestion of the enzyme or with the presence in the periplasm of its producer of a nonactive precursor whose activation may lead to a change in the molecular mass. Pseudomonas aeruginosa protease is capable of cleaving high-molecular proteins into low-molecular ones, which are taken up by the microbial cell and serve as a source of nutrition. When injected into the bloodstream of animals, purified protease produces haemorrhagic lesions in internal organs; its subcutaneous injection provokes haemorrhage in the skin and subcutaneous tissues. Manifestation of high P. aeruginosa virulence on a model of burnt mouse skin requires that not only exotoxin A but also protease be produced. The protease is immunogenic and has, in toxoid form, been used experimentally in a multicomponent vaccine.