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Protein-mediated biofilm development in Staphylococcus aureus

AuthorsVergara-Irigaray, Marta ; Merino, N.; García, Begoña ; Latasa Osta, Cristina ; Ruiz de los Mozos, Igor ; Solano Goñi, Cristina ; Valle Turrillas, Jaione ; Toledo-Arana, Alejandro ; Penadés, José R. ; Lasa, Íñigo
Issue DateJan-2010
CitationJoint Annual Seminar on the Projects of the 1st and 2nd calls of the ERA-NET PathoGenoMics (2010)
AbstractDespite the general agreement that the exopolysaccharides plays a key role in biofilm development, increasing number of evidences indicate the existence of proteinaceous- dependent biofilm matrix. The existence of biofilm matrixes of different composition suggests that each matrix might confer different properties to the embedded bacteria. Because the proteomic analysis of the exopolysaccharide matrix of Salmonella enteritidis and Staphylococcus aureus revealed the presence of very few proteins, whose presence is not specific for biofilm matrix, we focused our e fforts to investigate protein-mediated biofilm development in S. aureus . The ultimate goal will be to understand the influence that biofilm matrix nature (polysaccharidic or proteinaceuos) has on embedded bacteria. For that, we first analyzed the protein-mediated biofilm matrix developed by some S. aureus strains in the absence of ArlRS two-component system. To identify the protein component responsible for the PIA/PNAG-independent biofilm development in arlRS mutants, fixed bacterial cells were digested with trypsin to yield a peptide mixture that was fractionated and analyzed by 2DnLC coupled to electrospray ionization and mass spec trometry. The results of the study revealed that overexpression of Protein A induced in tercellular aggregation and biofilm development. Exogenous addition of purified protein A or supernatants containing secreted protein A to growth media induced biofilm development, indica ting that, at least, protein A can promote biofilm development without being covalently anchored to the cell wall. On the other hand, we investigated a clinical S. aureus MRSA strain able to switch between proteinaceous and polysaccharidic biofilm matrix depending on the environmental conditions. Systematic disruption of each member of the LPXTG surface protein family identified fibronectin-binding proteins (FnBPs) as components of a proteinaceous biofilm formed in Trypticase soy broth- glucose, whereas a PIA/PNAG-dependent biofilm was produced under osmotic stress conditions. The induction of FnBP levels due to the activation of a LexA-dependent SOS response or FnBP overexpression from a mu lticopy plasmid enhanced biofilm development, suggesting a direct relationship between the FnBP levels and the strength of the multicellular phenotype. Interestingly, scanning electron microscopy revealed that cells growing in these protein-mediated biofilms formed highly dense aggregates without any detectable extracellular matrix, whereas cells in a PIA/PNAG -dependent biofilm were embedded in an abundant extracellular material. Finally, we compared the contribution of protein-mediated biofilm with respect to exopolysaccharide-mediated biofilm to colonization of subcutaneously implanted catheters. Unexpectedly, the results revealed that both Protein A and FnBP mutants displayed a significantly lower capacity to develop biofilm on implanted catheters than their corresponding isogenic PIA/PNAG-deficient mutants. These results strongly suggest that protein-mediated biofilms might play a more relevant role than exopolysaccharide-mediated biofilm in the colonization of the implanted devices.
DescriptionPóster presentado en el Joint Annual Seminar on the Projects of the 1st and 2nd calls of the ERA-NET PathoGenoMics, celebrado en Costa Adeje (Tenerife) el 18 y 19 de enero de 2010.
Appears in Collections:(IDAB) Comunicaciones congresos
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