title: Translation Elongation Factor Tuf of Acinetobacter baumannii Is a Plasminogen-Binding Protein.
abstract: Acinetobacter baumannii is an important nosocomial pathogen, causing a variety of opportunistic infections of the skin, soft tissues and wounds, urinary tract infections, secondary meningitis, pneumonia and bacteremia. Over 63% of A. baumannii infections occurring in the United States are caused by multidrug resistant isolates, and pan-resistant isolates have begun to emerge that are resistant to all clinically relevant antibiotics. The complement system represents the first line of defense against invading pathogens. However, many A. baumannii isolates, especially those causing severe bacteremia are resistant to complement-mediated killing, though the underlying mechanisms remain poorly understood. Here we show for the first time that A. baumannii binds host-derived plasminogen and we identify the translation elongation factor Tuf as a moonlighting plasminogen-binding protein that is exposed on the outer surface of A. baumannii. Binding of plasminogen to Tuf is at least partly dependent on lysine residues and ionic interactions. Plasminogen, once bound to Tuf can be converted to active plasmin and proteolytically degrade fibrinogen as well as the key complement component C3b. Thus, Tuf acts as a multifunctional protein that may contribute to virulence of A. baumannii by aiding in dissemination and evasion of the complement system.
authors.affiliation: Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Frankfurt, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Koenigs
authors.affiliation: Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, Jena, Germany; Friedrich Schiller University, Jena, Germany.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Zipfel
authors.affiliation: Institute of Medical Microbiology and Infection Control, University Hospital of Frankfurt, Frankfurt, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Kraiczy
mesh_terms: D040981:Acinetobacter baumannii / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D008239:Lysine / Q000378:metabolism; D009994:Osmolar Concentration; D010445:Peptide Elongation Factors / Q000737:chemistry / Q000378:metabolism*; D010958:Plasminogen / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D001426:Bacterial Proteins; D010445:Peptide Elongation Factors; D005340:Fibrinogen; D010958:Plasminogen; D008239:Lysine