Bap, a Staphylococcus aureus Surface Protein Involved in Biofilm Formation

Abstract

Identification of new genes involved in biofilm formation is needed to understand the molecular basis of strain variation and the pathogenic mechanisms implicated in chronic staphylococcal infections. A biofilmproducing Staphylococcus aureus isolate was used to generate biofilm-negative transposon (Tn917) insertion mutants. Two mutants were found with a significant decrease in attachment to inert surfaces (early adherence), intercellular adhesion, and biofilm formation. The transposon was inserted at the same locus in both mutants. This locus (bap [for biofilm associated protein]) encodes a novel cell wall associated protein of 2,276 amino acids (Bap), which shows global organizational similarities to surface proteins of gram-negative (Pseudomonas aeruginosa and Salmonella enterica serovar Typhi) and gram-positive (Enteroccocus faecalis) microorganisms. Bap's core region represents 52% of the protein and consists of 13 successive nearly identical repeats, each containing 86 amino acids. bap was present in a small fraction of bovine mastitis isolates (5% of the 350 S. aureus isolates tested), but it was absent from the 75 clinical human S. aureus isolates analyzed. All staphylococcal isolates harboring bap were highly adherent and strong biofilm producers. In a mouse infection model bap was involved in pathogenesis, causing a persistent infection.

A family of putative MSCRAMMs from Enterococcus faecalis

“…By using the 3D-PSSM-fold recognition server (Kelley et al, 2000), we initially found 14 enterococcal CWA proteins with predicted Ig-like folds among the panel of 29 putative CWA proteins identified by us. Four of these are highly conserved aggregation substance (Galli et al, 1990(Galli et al, , 1992 homologues (77 % overall identity in multiple alignment) and one shows significant similarity (31 % identity over 1457 aa) to the biofilm-associated protein (Bap) of S. aureus (Cucarella et al, 2001). As we were focusing on novel and uncharacterized CWA proteins with MSCRAMM-like structural features, we chose the remaining nine proteins (EF0089, EF1091, EF1092, EF1093, EF1099, EF1269, EF1824, EF2224 and EF3023; TIGR annotation locus names have been used throughout this study) for further investigation (Fig.…”

The complete genome sequence of the meat-borne lactic acid bacterium Lactobacillus sakei 23K

“…One candidate for biofilm formation is a large 1,987-residue protein (LSA0534) composed of 15 perfectly conserved 100-amino-acid repeats and of an LPXTG motif (PF00746) involved in covalent anchoring to the cell wall. It demonstrates 37% similarity to Biofilm Associated Protein (BAP) found in bovine Staphylococcus aureus strains 33 . We further identified four paralogous proteins predicted to mediate autoaggregation and adherence to collagen 34 .…”

Heterologous Expression and Purification of a 238 kDa Large Biofilm Associated Surface Protein (Bap) in Escherichia coli

“…In general, pathogenicity and persistence of these infections are associated with biofilm forming capability. Many surface proteins are reported to be involved in biofilm formation such as SasG [14], FnBPA and FnBPB [15], and the biofilm-associated protein Bap [3]. The Bap protein is encoded by a 6831 bp long bap gene.…”

“…One of the factors is the expression of Biofilm-associated protein which confers the capacity to form biofilm. It also plays a crucial role in bacterial infection process even in the absence of ica operon, which is responsible for polysaccharide intercellular adhesion (PIA)/poly-β-1,6-N-acetylglucosamine (PNAG) synthesis [3]. Bap was the first protein among the family of large surface proteins that is reported to be involved in initial attachment to surfaces and assist in cell-cell interactions [4].…”

“…The work on Bap protein is still in infancy and till date, besides the pioneering work by Cucarella et al [3], there is not much information available. In one of our previous studies, we showed that how Bap is important in S. aureus biofilm stability and how non-antibiotic factors such as Calcium ion concentration and proteinase K can be used to modulate the S. aureus biofilms [9][10][11].…”