title: Biofilm-associated proteins: news from Acinetobacter.
abstract: BACKGROUND
  A giant protein called BAP (biofilm-associated protein) plays a role in biofilm formation and adhesion to host cells in A. baumannii. Most of the protein is made by arrays of 80-110 aa modules featuring immunoglobulin-like (Ig-like) motifs.
  
  
  RESULTS
  The survey of 541 A. baumannii sequenced strains belonging to 108 STs (sequence types) revealed that BAP is highly polymorphic, distinguishable in three main types for changes both in the repetitive and the COOH region. Analyzing the different STs, we found that 29 % feature type-1, 40 % type-2 BAP, 11 % type-3 BAP, 20 % lack BAP. The type-3 variant is restricted to A. baumannii, type-1 and type-2 BAP have been identified also in other species of the Acinetobacter calcoaceticus-baumannii (ACB) complex. A. calcoaceticus and A. pittii also encode BAP-like proteins in which Ig-like repeats are replaced by long tracts of alternating serine and aspartic acid residues. We have identified in species of the ACB complex two additional proteins, BLP1 and BLP2 (BAP-like proteins 1 and 2) which feature Ig-like repeats, share with BAP a sequence motif at the NH2 terminus, and are similarly expressed in stationary growth phase. The knock-out of either BLP1 or BLP2 genes of the A. baumannii ST1 AYE strain severely affected biofilm formation, as measured by comparing biofilm biomass and thickness, and adherence to epithelial cells. BLP1 is missing in the majority of type-3 BAP strains. BLP2 is largely conserved, but is frequently missing in BAP-negative cells.
  
  
  CONCLUSIONS
  Multiple proteins sharing Ig-like repeats seem to be involved in biofilm formation. The uneven distribution of the different BAP types, BLP1, and BLP2 is highly indicative that alternative protein complexes involved in biofilm formation are assembled in different A. baumannii strains.
authors.affiliation: Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5, Naples, 80131, Italy. edegrego@unina.it.
authors.forename: Eliana
authors.initials: E
authors.lastname: De Gregorio
authors.affiliation: Dipartimento di Sanità Pubblica, Università Federico II, Via Sergio Pansini 5, 80131, Naples, Italy. mariateresa.88@libero.it.
authors.forename: Mariateresa
authors.initials: M
authors.lastname: Del Franco
authors.affiliation: Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5, Naples, 80131, Italy. mariannamartinucci@libero.it.
authors.forename: Marianna
authors.initials: M
authors.lastname: Martinucci
authors.affiliation: Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5, Naples, 80131, Italy. emanuelaroscetto@gmail.com.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Roscetto
authors.affiliation: Dipartimento di Sanità Pubblica, Università Federico II, Via Sergio Pansini 5, 80131, Naples, Italy. rafzarri@unina.it.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Zarrilli
authors.affiliation: Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università Federico II, Via Sergio Pansini 5, Naples, 80131, Italy. dinocera@unina.it.
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Di Nocera
mesh_terms: D040981:Acinetobacter baumannii / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001980:Bronchi / Q000382:microbiology; D002460:Cell Line; D018740:Genetic Heterogeneity; D016680:Genome, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins