title: Identification and characterization of an Acinetobacter baumannii biofilm-associated protein.
abstract: We have identified a homologue to the staphylococcal biofilm-associated protein (Bap) in a bloodstream isolate of Acinetobacter baumannii. The fully sequenced open reading frame is 25,863 bp and encodes a protein with a predicted molecular mass of 854 kDa. Analysis of the nucleotide sequence reveals a repetitive structure consistent with bacterial cell surface adhesins. Bap-specific monoclonal antibody (MAb) 6E3 was generated to an epitope conserved among 41% of A. baumannii strains isolated during a recent outbreak in the U.S. military health care system. Flow cytometry confirms that the MAb 6E3 epitope is surface exposed. Random transposon mutagenesis was used to generate A. baumannii bap1302::EZ-Tn5, a mutant negative for surface reactivity to MAb 6E3 in which the transposon disrupts the coding sequence of bap. Time course confocal laser scanning microscopy and three-dimensional image analysis of actively growing biofilms demonstrates that this mutant is unable to sustain biofilm thickness and volume, suggesting a role for Bap in supporting the development of the mature biofilm structure. This is the first identification of a specific cell surface protein directly involved in biofilm formation by A. baumannii and suggests that Bap is involved in intercellular adhesion within the mature biofilm.
authors.affiliation: Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, University at Buffalo, The State University of New York 14214, USA.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Loehfelm
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Luke
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Campagnari
mesh_terms: D000151:Acinetobacter Infections / Q000453:epidemiology / Q000382:microbiology; D040981:Acinetobacter baumannii / Q000235:genetics / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D004196:Disease Outbreaks; D005434:Flow Cytometry; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008889:Military Personnel; D008969:Molecular Sequence Data; D009154:Mutation
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; C425726:Bap protein, Staphylococcus aureus; D008565:Membrane Proteins