Identification and characterization of an Acinetobacter baumannii biofilm-associated protein

J Bacteriol. 2008 Feb;190(3):1036-44. doi: 10.1128/JB.01416-07. Epub 2007 Nov 16.

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acinetobacter Infections / epidemiology
  • Acinetobacter Infections / microbiology
  • Acinetobacter baumannii / genetics
  • Acinetobacter baumannii / growth & development*
  • Acinetobacter baumannii / isolation & purification
  • Acinetobacter baumannii / metabolism
  • Amino Acid Sequence
  • Antibodies, Bacterial / biosynthesis
  • Antibodies, Bacterial / immunology
  • Antibodies, Monoclonal / biosynthesis
  • Antibodies, Monoclonal / immunology
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / immunology
  • Bacterial Proteins / metabolism*
  • Biofilms / growth & development*
  • Disease Outbreaks
  • Flow Cytometry
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / immunology
  • Membrane Proteins / metabolism*
  • Military Personnel
  • Molecular Sequence Data
  • Mutation

Substances

  • Antibodies, Bacterial
  • Antibodies, Monoclonal
  • Bacterial Proteins
  • Bap protein, Staphylococcus aureus
  • Membrane Proteins

Associated data

  • GENBANK/EU117203