title: Protease IV, a unique extracellular protease and virulence factor from Pseudomonas aeruginosa.
abstract: Comparisons of virulence between a Pseudomonas parent strain and an isogenic mutant devoid of protease IV have demonstrated a significant role for this enzyme during infection. We have characterized purified Pseudomonas aeruginosa protease IV in terms of its biochemical and enzymatic properties, and found it to be a unique extracellular protease. The N-terminal decapeptide sequence of protease IV is not homologous with any published protein sequence. Protease IV has a molecular mass of 26 kDa, an isoelectric point of 8.70, and optimum enzymatic activity at pH 10.0 and 45 degreesC. Purified protease IV demonstrates activity for the carboxyl side of lysine-containing peptides and can digest a number of biologically important proteins, including immunoglobulin, complement components, fibrinogen, and plasminogen. Protease IV is not inhibited by thiol-, carboxyl-, or metalloproteinase inhibitors. The total loss of enzyme activity in the presence of N-p-tosyl-L-chloromethyl ketone and the partial inhibition of enzyme activity by diisopropyl fluorophosphate or phenylmethylsulfonyl fluoride imply that protease IV is a serine protease. Inhibition by dithiothreitol and beta-mercaptoethanol suggests that intramolecular disulfide bonds are essential for enzyme activity. The characteristics of this enzyme suggest that inhibitors of serine proteases could be developed into a medication designed to arrest tissue damage during Pseudomonas infection.
authors.affiliation: Department of Microbiology, Immunology, and Parasitology, Louisiana State University Eye Center, Louisiana State University Medical Center, School of Medicine, New Orleans, Louisiana 70112, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Engel
authors.forename: J M
authors.initials: JM
authors.lastname: Hill
authors.forename: A R
authors.initials: AR
authors.lastname: Caballero
authors.forename: L C
authors.initials: LC
authors.lastname: Green
authors.forename: R J
authors.initials: RJ
authors.lastname: O'Callaghan
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009842:Oligopeptides / Q000378:metabolism; D009997:Osmotic Pressure; D010447:Peptide Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D011552:Pseudomonas Infections / Q000188:drug therapy; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology* / Q000472:pathogenicity; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D009842:Oligopeptides; D011480:Protease Inhibitors; C034172:chromozym PL; D010447:Peptide Hydrolases; C030732:protease IV