Translation Elongation Factor Tuf of Acinetobacter baumannii Is a Plasminogen-Binding Protein

• Published in: PloS one 2015-07, Vol.10 (7), p.e0134418-e0134418
• Main Authors: Koenigs, Arno, Zipfel, Peter F, Kraiczy, Peter
• Format: Article
• Language: English
• Subjects: Acanthamoeba; Acinetobacter; Acinetobacter baumannii; Acinetobacter baumannii - metabolism; Antibiotics; Bacteremia; Bacterial Proteins - metabolism; Borrelia burgdorferi; Casualties; Chemical properties; Complement; Complement component C3b; Complement system; Disease control; Elongation; Fibrin; Fibrinogen; Fibrinogen - metabolism; Health aspects; Hospitals; Humans; Infections; Ionic interactions; Legionella; Legionnaires disease; Leptospira interrogans; Lysine; Lysine - metabolism; Meningitis; Microorganisms; Multidrug resistance; Nosocomial infection; Nosocomial infections; Osmolar Concentration; Pathogens; Peptide Elongation Factors - chemistry; Peptide Elongation Factors - metabolism; Plasmin; Plasminogen - metabolism; Plasminogen-binding protein; Pneumonia; Protein Binding; Proteins; Pseudomonas aeruginosa; Skin; Soft tissues; Streptococcus; Streptococcus infections; Tissues; Translation; Translation elongation; Urinary tract; Virulence; Wounds
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0134418

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.