Is the GehD lipase from Staphylococcus epidermidis a collagen binding adhesin

The opportunistic human pathogen Staphylococcus epidermidis is the major cause of nosocomial biomaterial infections. S. epidermidis has the ability to attach to indwelling materials coated with extracellular matrix proteins such as fibrinogen, fibronectin, vitronectin, and collagen. To identify the proteins necessary for S. epidermidis attachment to collagen, we screened an expression library using digoxigenin-labeled collagen as well as two monoclonal antibodies generated against the Staphylococcus aureus collagen-adhesin, Cna, as probes. These monoclonal antibodies recognize collagen binding epitopes on the surface of S. aureus and S. epidermidis cells. Using this approach, we identified GehD, the extracellular lipase originally found in S. epidermidis 9, as a collagen-binding protein. Despite the monoclonal antibody cross-reactivity, the GehD amino acid sequence and predicted structure are radically different from those of Cna. The mature GehD circular dichroism spectra differs from that of Cna but strongly resembles that of a mammalian cell-surface collagen binding receptor, known as the alpha(1) integrin I domain, suggesting that they have similar secondary structures. The GehD protein is translated as a preproenzyme, secreted, and post-translationally processed into mature lipase. GehD does not have the conserved LPXTG C-terminal motif present in cell wall-anchored proteins, but it can be detected in lysostaphin cell wall extracts. A recombinant version of mature GehD binds to collagens type I, II, and IV adsorbed onto microtiter plates in a dose-dependent saturable manner. Recombinant, mature GehD protein and anti-GehD antibodies can inhibit the attachment of S. epidermidis to immobilized collagen. These results provide evidence that GehD may be a bi-functional molecule, acting not only as a lipase but also as a cell surface-associated collagen adhesin

The Signal Peptide of Staphylococcus aureus Panton Valentine Leukocidin LukS Component Mediates Increased Adhesion to Heparan Sulfates

Staphylococcus aureus necrotizing pneumonia is a severe disease caused by S. aureus strains carrying the Panton Valentine leukocidin (PVL) genes (lukS-PV & lukF-PV) encoded on various bacteriophages (such as phiSLT). Clinical PVL+ strains isolated from necrotizing pneumonia display an increased attachment to matrix molecules (type I and IV collagens and laminin), a phenotype that could play a role in bacterial adhesion to damaged airway epithelium during the early stages of necrotizing pneumonia (J Infect Dis 2004; 190: 1506–15). To investigate the basis of the observed adhesion of S. aureus PVL+ strains, we compared the ability of PVL+ and their isogenic PVL− strains to attach to various immobilized matrix molecules. The expression of recombinant fragments of the PVL subunits and the addition of synthetic peptides indicated that the processed LukS-PV signal peptide (LukS-PV SP) was sufficient to significantly enhance the ability of S. aureus to attach to extracellular matrix (ECM) components. Furthermore, we showed that adhesion to ECM components was inhibited by heparin and heparan sulfates (HS) suggesting that in vivo, HS could function as a molecular bridge between the matrix and S. aureus expressing the LukS-PV signal peptide. Site directed mutagenesis, biochemical and structural analyses of the LukS-PV signal peptide indicate that this peptide is present at the S. aureus surface, binds to HS in solid phase assay, and mediates the enhanced S. aureus matrix component adhesion. Our data suggests that after its cleavage by signal peptidase, the signal peptide is released from the membrane and associates to the cell wall through its unique C-terminus sequence, while its highly positively charged N-terminus is exposed on the bacterial surface, allowing its interaction with extracellular matrix-associated HS. This mechanism may provide a molecular bridge that enhances the attachment of the S. aureus PVL+ strains to ECM components exposed at damaged epithelial sites

A Structural Model of the Staphylococcus aureus ClfA–Fibrinogen Interaction Opens New Avenues for the Design of Anti-Staphylococcal Therapeutics

The fibrinogen (Fg) binding MSCRAMM Clumping factor A (ClfA) from Staphylococcus aureus interacts with the C-terminal region of the fibrinogen (Fg) γ-chain. ClfA is the major virulence factor responsible for the observed clumping of S. aureus in blood plasma and has been implicated as a virulence factor in a mouse model of septic arthritis and in rabbit and rat models of infective endocarditis. We report here a high-resolution crystal structure of the ClfA ligand binding segment in complex with a synthetic peptide mimicking the binding site in Fg. The residues in Fg required for binding to ClfA are identified from this structure and from complementing biochemical studies. Furthermore, the platelet integrin αIIbβ3 and ClfA bind to the same segment in the Fg γ-chain but the two cellular binding proteins recognize different residues in the common targeted Fg segment. Based on these differences, we have identified peptides that selectively antagonize the ClfA-Fg interaction. The ClfA-Fg binding mechanism is a variant of the “Dock, Lock and Latch” mechanism previously described for the Staphylococcus epidermidis SdrG–Fg interaction. The structural insights gained from analyzing the ClfANFg peptide complex and identifications of peptides that selectively recognize ClfA but not αIIbβ3 may allow the design of novel anti-staphylococcal agents. Our results also suggest that different MSCRAMMs with similar structural organization may have originated from a common ancestor but have evolved to accommodate specific ligand structures

The genetic architecture of type 2 diabetes

The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of heritability. To test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole genome sequencing in 2,657 Europeans with and without diabetes, and exome sequencing in a total of 12,940 subjects from five ancestral groups. To increase statistical power, we expanded sample size via genotyping and imputation in a further 111,548 subjects. Variants associated with type 2 diabetes after sequencing were overwhelmingly common and most fell within regions previously identified by genome-wide association studies. Comprehensive enumeration of sequence variation is necessary to identify functional alleles that provide important clues to disease pathophysiology, but large-scale sequencing does not support a major role for lower-frequency variants in predisposition to type 2 diabetes

Antibodies recognizing a highly expressed putative antigen of CA-MRSA and methods of use

The present invention provides MSCRAMM® proteins from S. aureus which are putative highly-expressed antigens from methicillin-resistant S. aureus, including communit-associated MRSA (CA-MRSA), and these antigens can thus be utilized in methods of generating antibodies capable of binding these antigens which can be useful in methods of treating or preventing infection from MRSA. The present invention is directed to these proteins, antibodies capable of binding these proteins, methods of generating said antibodies, nucleic acids coding for said proteins, and pharmaceutical compositions or vaccines which include the proteins or antibodies of the present invention in combination with a pharmaceutically acceptable vehicle, carrier or excipient.U

Antibodies recognizing a highly expressed putative antigen of CA-MRSA and methods of use

The present invention provides MSCRAMM® proteins from S. aureus which are putative highly-expressed antigens from methicillin-resistant S. aureus, including communit-associated MRSA (CA-MRSA), and these antigens can thus be utilized in methods of generating antibodies capable of binding these antigens which can be useful in methods of treating or preventing infection from MRSA. The present invention is directed to these proteins, antibodies capable of binding these proteins, methods of generating said antibodies, nucleic acids coding for said proteins, and pharmaceutical compositions or vaccines which include the proteins or antibodies of the present invention in combination with a pharmaceutically acceptable vehicle, carrier or excipient.U

Antibodies recognizing a highly expressed putative antigen of CA-MRSA and methods of use

The present invention provides MSCRAMM? proteins from S. aureus which are putative highly-expressed antigens from methicillin-resistant S. aureus, including communit-associated MRSA (CA-MRSA), and these antigens can thus be utilized in methods of generating antibodies capable of binding these antigens which can be useful in methods of treating or preventing infection from MRSA. The present invention is directed to these proteins, antibodies capable of binding these proteins, methods of generating said antibodies, nucleic acids coding for said proteins, and pharmaceutical compositions or vaccines which include the proteins or antibodies of the present invention in combination with a pharmaceutically acceptable vehicle, carrier or excipient.U

Antibodies recognizing a highly expressed putative antigen of CA-MRSA and methods of use

The present invention provides MSCRAMM? proteins from S. aureus which are putative highly-expressed antigens from methicillin-resistant S. aureus, including communit-associated MRSA (CA-MRSA), and these antigens can thus be utilized in methods of generating antibodies capable of binding these antigens which can be useful in methods of treating or preventing infection from MRSA. The present invention is directed to these proteins, antibodies capable of binding these proteins, methods of generating said antibodies, nucleic acids coding for said proteins, and pharmaceutical compositions or vaccines which include the proteins or antibodies of the present invention in combination with a pharmaceutically acceptable vehicle, carrier or excipient.U

Pediatric Antibody Response to Community-Acquired Staphylococcus aureus Infection Is Directed to Panton-Valentine Leukocidin▿

We examined the antibody responses of pediatric patients infected with community-associated Staphylococcus aureus isolates. The data show that patients infected with Panton-Valentine leukocidin (PVL)-positive strains developed a dominant immunoglobulin G anti-PVL antibody response that correlates with markers of inflammation