Deletion of the prc (tsp) gene provides evidence for additional tail-specific proteolytic activity in Escherichia coli K-12.

The Escherichia coli protease Prc (Tsp) exhibits specificity in vitro for proteins with nonpolar carboxyl termini. To determine whether Prc is responsible for the selective degradation in vivo of proteins with nonpolar carboxyl termini, we constructed a prc (tsp) deletion strain. Deletion of the prc gene did not prevent the rapid intracellular degradation of a variant of the amino-terminal domain of lambda repressor with a nonpolar carboxyl terminus, even though this protein is a substrate for Prc in vitro. Our results indicate that at least one additional carboxy-terminal-specific proteolytic system must exist in E. coli.