title: Serine protease PKF of Acinetobacter baumannii results in serum resistance and suppression of biofilm formation.
abstract: Acinetobacter baumannii is an important nosocomial pathogen. Infections are often preceded by intubation or catheter use, promoting the formation of biofilm, and some strains are able to cause severe cases of bacteremia because of their ability to resist killing by complement. We identified a secreted serine protease, termed "PKF," that provided resistance to complement killing and suppressed biofilm formation. Serum resistance was abrogated in A. baumannii treated with protease inhibitors, as well as in a PKF-negative mutant. Serum resistance could be restored by recombinant PKF, which was shown to reduce the complement activity of normal human serum by almost 50%. PKF was shown to inhibit biofilm formation, because the PKF-negative mutant and wild-type A. baumannii treated with protease inhibitors produced biofilm that could be inhibited by addition of recombinant PKF. Our data indicate that PKF is required for serum resistance and that it suppresses biofilm formation in A. baumannii.
authors.affiliation: Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216, USA.
authors.forename: Lauren B
authors.initials: LB
authors.lastname: King
authors.forename: Michael K
authors.initials: MK
authors.lastname: Pangburn
authors.forename: Larry S
authors.initials: LS
authors.lastname: McDaniel
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects*; D001770:Blood Bactericidal Activity; D003001:Cloning, Molecular; D003170:Complement Pathway, Alternative; D024881:Drug Resistance, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D013450:Sulfones / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D013450:Sulfones; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D057057:Serine Proteases