Structure and functions of bacterial proteinase precursors

The data on the precursors of bacterial proteases were generalized. The structure and special features of processing of the precursors of bacillary subtilisins, the alpha-lytic protease from Lysobacter enzymogenes and the related chymotrypsin-like proteases from Streptomyces griseus, and the metalloproteases from bacilli and Pseudomonas aeruginosa were discussed. The approaches to producing the precursors and the protease propeptides and to in vitro characterizing them were particularly analyzed. The following physiological functions of the propeptides within the protease precursors were considered probable: (a) inhibition of the proteases to protect the host cells from the proteolytic damage; (b) participation in the folding of the mature enzyme; and (c) providing for the protease interaction with the bacterial cell surveillance mechanisms, including protease translocation through the cell wall.