Lysis and killing of bacteria by lysosomal proteinases

Abstract

The bacteriolytic and bactericidal effects of the human proteinases cathepsin B, cathepsin D, cathepsin G, and elastase were investigated. Cathepsin G and elastase were 5 to 10% as active as egg white lysozyme in the lysis of Micrococcus lysodeikticus. All four enzymes slowly lysed the lysozyme-resistant Staphylococcus aureus. The gram-negative Acinetobacter 199A was rendered sensitive to lysozyme by all of the proteinases. Only elastase caused marked proteolysis of the outer membrane, which would permit access by lysozyme to the underlying peptidoglycan. When the surface layer of regularly arranged a protein was removed, however, the outer membrane proteins became susceptible to the other proteinases. Cathepsin G, elastase, and cathepsin D were bactericidal to Acinetobacter 199A. The bactericidal activity of cathepsin D was shown to be dependent on enzymatic activity, unlike that of cathepsin G, which was related to its cationic nature.

How human neutrophils kill and degrade microbes: an integrated view

“…Of interest, the augmented killing is not compromised by heat‐inactivating HNE enzymatic activity, suggesting that elastolytic action is not a prerequisite for synergy. The independence of anti‐microbial action from enzymatic activity has been observed in studies of PMN– Borrelia interactions (72) and applies to other serprocidins, including cathepsin G (33, 73). Given the cationic nature common to this group of granule proteins, it is reasonable to speculate that their strong electrostatic interactions with the microbial surface disrupt the integrity of the organism, rendering potential targets more accessible to attack.…”

“…Additional proteins have been isolated from the cytosolic complex [e.g. p40 phox (29–35)] or shown in broken cell systems to modulate activity [e.g. MRP8/14 (36–38)], indicating that all the regulatory elements of this important system and their specific function remain to be completely identified.…”

Effect of proteolytic enzymes on the lysis and growth of oral bacteria

“…These bacteria appeared to be more sensitive to lysis by nonspecific protease activity (proteinase K) than by specific protease activity (trypsin and chymotrypsin). The ability of proteolytic enzymes to lyse bacteria has been the topic of very few reports (2,11,12,25). Kaur et al (12) demonstrated that elastase purified from Psettdomotias aerttgitwsa caused lysis of freshly cultured cells of grampositive and gram-negative bacteria.…”

Changes in cervical neutrophil elastase levels during the menstrual cycle

“…It is released from neutrophils and accumulates at sites of inflammation when leukocytes are activated by bacterial infection. NE degrades not only extracellular matrix components such as fibrin, fibronectin, and collagen [6][7][8] but also the bacterial wall [9]. Clinically, NE is used as a sensitive serum marker for inflammation [10].…”