Fibronectin-binding proteins are required for biofilm formation by community-associated methicillin-resistant<i>Staphylococcus aureus</i>strain LAC

Staphylococcus aureus is a commensal bacterium that has the ability to cause superficial and deep-seated infections. Like several other invasive pathogens, S. aureus can capture plasminogen from the human host where it can be converted to plasmin by host plasminogen activators or by endogenously expressed staphylokinase. This study demonstrates that sortase-anchored cell wall-associated proteins are responsible for capturing the bulk of bound plasminogen. Two cell wall-associated proteins, the fibrinogen-and fibronectin-binding proteins A and B, were found to bind plasminogen, and one of them, FnBPB, was studied in detail. Plasminogen captured on the surface of S. aureusor Lactococcus lactis-expressing FnBPB could be activated to the potent serine protease plasmin by staphylokinase and tissue plasminogen activator. Plasminogen bound to recombinant FnBPB with a K D of 0.532 M as determined by surface plasmon resonance. Plasminogen binding did not to occur by the same mechanism through which FnBPB binds to fibrinogen. Indeed, FnBPB could bind both ligands simultaneously indicating that their binding sites do not overlap. The N3 subdomain of FnBPB contains the full plasminogen-binding site, and this includes, at least in part, two conserved patches of surface-located lysine residues that were recognized by kringle 4 of the host protein.

show abstract

“…12 FnBPA. Amino acid sequence alignments of isotypes I-VII of FnBPB were used to identify conserved lysine residues in subdomain N3.…”

Section: Bacterial Strainmentioning

confidence: 99%

“…They can also engage in homophilic interactions to form dimers, and when two FnBP molecules on neighboring cells interact, this can lead to cell accumulation during biofilm formation (10). The HA-MRSA strain BH1CC and the CA-MRSA strain LAC form biofilm that is dependent on FnBPs (11,12).…”

mentioning

confidence: 99%

Molecular Interactions of Human Plasminogen with Fibronectin-binding Protein B (FnBPB), a Fibrinogen/Fibronectin-binding Protein from Staphylococcus aureus

Pietrocola

Nobile

Gianotti

et al. 2016

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…Initial surface attachment is dependent on bacterial surface molecules such as the S. aureus murein hydrolase AtlA, teichoic acids, and fibronectin-binding proteins (FnBPs) (17)(18)(19)(20). After attachment to the surface, the bacteria multiply and produce the extracellular polymeric matrix.…”

mentioning

confidence: 99%

Modulation of Staphylococcus aureus Biofilm Matrix by Subinhibitory Concentrations of Clindamycin

Schilcher

Andreoni

Haunreiter

et al. 2016

Antimicrob Agents Chemother

View full text Add to dashboard Cite

Staphylococcus aureus biofilms are extremely difficult to treat. They provide a protected niche for the bacteria, rendering them highly recalcitrant toward host defenses as well as antibiotic treatment. Bacteria within a biofilm are shielded from the immune system by the formation of an extracellular polymeric matrix, composed of polysaccharides, extracellular DNA (eDNA), and proteins. Many antibiotics do not readily penetrate biofilms, resulting in the presence of subinhibitory concentrations of antibiotics. Here, we show that subinhibitory concentrations of clindamycin triggered a transcriptional stress response in S. aureus via the alternative sigma factor B ( B ) and upregulated the expression of the major biofilm-associated genes atlA, lrgA, agrA, the psm genes, fnbA, and fnbB. Our data suggest that subinhibitory concentrations of clindamycin alter the ability of S. aureus to form biofilms and shift the composition of the biofilm matrix toward higher eDNA content. An understanding of the molecular mechanisms underlying biofilm assembly and dispersal in response to subinhibitory concentrations of clinically relevant antibiotics such as clindamycin is critical to further optimize antibiotic treatment strategies of biofilm-associated S. aureus infections. Staphylococcus aureus is a major cause of both health care-related and community-associated (CA) infections. The Grampositive human-pathogenic bacterium produces and secretes a range of toxins and enzymes leading to acute infections such as bacteremia and skin abscesses (1, 2). In addition, most S. aureus strains are capable of biofilm formation and can persist in host tissues such as the bone, leading to chronic osteomyelitis, or on implanted medical devices such as vascular catheters, vascular grafts, heart valves, and prosthetic joints (3-5). Biofilm-associated infections are extremely difficult to treat, and these chronic or relapsing infections typically require prolonged antibiotic treatment or removal of the device (6-8). Antibiotic resistance of bacteria within a biofilm may result from slow growth, phenotypic heterogeneity, persister cell formation, and inactivation or reduced penetration of the antibiotic (9, 10). Diffusion of the antibiotic through biofilm cell clusters is dependent on the thickness and the composition of the extracellular polymeric matrix (9, 11). The slow transport within biofilms suggests that the bacteria may encounter subinhibitory concentrations of antibiotics. Previous studies have shown that low doses of different antibiotics trigger biofilm formation (12, 13) and lead to dramatic alterations in bacterial gene expression in S. aureus (14).Biofilm formation proceeds in at least three phases: initial attachment, biofilm maturation, and dispersal (15, 16). Initial surface attachment is dependent on bacterial surface molecules such as the S. aureus murein hydrolase AtlA, teichoic acids, and fibronectin-binding proteins (FnBPs) (17)(18)(19)(20). After attachment to the surface, the bacteria multiply and produce the extracellular...

show abstract

“…Methicillin resistance is mediated by mecA, a gene that encodes a novel cell wall transpeptidase with low affinity for most ␤-lactam antibiotics (4). Biofilm formation is mediated by extracellular polymeric substances (EPS), including proteinaceous adhesins, such as fibronectin binding proteins A and B (5,6); extracellular DNA (eDNA) (7); and polysaccharides, such as poly-N-acetyl-D-glucosamine (PNAG), also known as polysaccharide intercellular adhesin (PIA) (3,(7)(8)(9). Methicillin resistance limits treatment options for MRSA, and biofilm formation confers additional antibiotic resistance that limits treatment efficacy.…”

mentioning

confidence: 99%

Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms

Mlynek

Callahan

Shimkevitch

et al. 2016

Antimicrob Agents Chemother

View full text Add to dashboard Cite

cPrevious studies showed that sub-MIC levels of ␤-lactam antibiotics stimulate biofilm formation in most methicillin-resistant Staphylococcus aureus (MRSA) strains. Here, we investigated this process by measuring the effects of sub-MIC amoxicillin on biofilm formation by the epidemic community-associated MRSA strain USA300. We found that sub-MIC amoxicillin increased the ability of USA300 cells to attach to surfaces and form biofilms under both static and flow conditions. We also found that USA300 biofilms cultured in sub-MIC amoxicillin were thicker, contained more pillar and channel structures, and were less porous than biofilms cultured without antibiotic. Biofilm formation in sub-MIC amoxicillin correlated with the production of extracellular DNA (eDNA). However, eDNA released by amoxicillin-induced cell lysis alone was evidently not sufficient to stimulate biofilm. Sub-MIC levels of two other cell wall-active agents with different mechanisms of action-D-cycloserine and fosfomycin-also stimulated eDNA-dependent biofilm, suggesting that biofilm formation may be a mechanistic adaptation to cell wall stress. Screening a USA300 mariner transposon library for mutants deficient in biofilm formation in sub-MIC amoxicillin identified numerous known mediators of S. aureus ␤-lactam resistance and biofilm formation, as well as novel genes not previously associated with these phenotypes. Our results link cell wall stress and biofilm formation in MRSA and suggest that eDNA-dependent biofilm formation by strain USA300 in low-dose amoxicillin is an inducible phenotype that can be used to identify novel genes impacting MRSA ␤-lactam resistance and biofilm formation.

show abstract

Fibronectin-binding proteins are required for biofilm formation by community-associated methicillin-resistantStaphylococcus aureusstrain LAC

Cited by 125 publications

References 44 publications

Molecular Interactions of Human Plasminogen with Fibronectin-binding Protein B (FnBPB), a Fibrinogen/Fibronectin-binding Protein from Staphylococcus aureus

Molecular Interactions of Human Plasminogen with Fibronectin-binding Protein B (FnBPB), a Fibrinogen/Fibronectin-binding Protein from Staphylococcus aureus

Modulation of Staphylococcus aureus Biofilm Matrix by Subinhibitory Concentrations of Clindamycin

Effects of Low-Dose Amoxicillin on Staphylococcus aureus USA300 Biofilms

Contact Info

Product

Resources

About