-!- This serine endopeptidase is essential for the clearance of denatured or aggregated proteins from the inner-membrane and periplasmic space in Escherichia coli. -!- Natural substrates of the enzyme include colicin A lysis protein, pilin subunits and MalS from E.coli. -!- The enzyme has weak peptidase activity with casein and other non- native substrates. -!- The peptidase acts as a chaperone at low temperatures but switches to a peptidase (heat shock protein) at higher temperatures. -!- Molecular chaperones and peptidases control the folded state of proteins by recognizing hydrophobic stretches of polypeptide that become exposed by misfolding or unfolding. -!- They then bind these hydrophobic substrates to prevent aggregation or assist in protein refolding. -!- If attempts at refolding fail, then irreversibly damaged proteins are degraded by peptidases such as this enzyme. -!- Belongs to peptidase family S1B.