Molecular characterization of the clumping factor (fibrinogen receptor) of Staphylococcus aureus

Abstract

Four mutants of Staphylococcus aureus strain Newman that were defective in the fibrinogen receptor (clumping factor) were isolated by transposon Tn917 mutagenesis. Southern hybridization analysis of the mutants identified transposon-host DNA junction fragments, one of which was cloned and used to generate a probe to identify and clone the wild-type clumping factor locus (clfA). The mutants failed to form clumps in soluble fibrinogen and adhered poorly to polymethylmethacrylate (PMMA) coverslips coated with fibrinogen. A single copy of the clfA gene, when introduced into the chromosome of the mutant strains, fully complemented the clumping deficiency of these strains and restored the ability of these mutants to adhere to fibrinogen-coated PMMA. In addition, the cloned clfA gene on a shuttle plasmid allowed the weakly clumping strain 8325-4 to form clumps with the same avidity as the wild-type strain Newman and also significantly enhanced the adherence of 8325-4 strains. Thus the formation of clumps in soluble fibrinogen correlated with adherence of bacteria to solid-phase fibrinogen. The clfA gene encodes a fibrinogen-binding protein with an apparent molecular mass of c. 130 kDa. The amino acid sequence of the protein was deduced from the DNA sequence; it was predicted that a 896 residue protein (molecular mass 92 kDa) would be expressed. The putative ClfA protein has features that suggest that it is associated with the cell surface. Furthermore it contains a novel 308 residue region comprising dipeptide repeats predominantly of Asp and Ser ending 28 residues upstream from the LPXTG motif common to wall-associated proteins. Significant homology was found between the ClfA protein and the fibronectin-binding proteins of S. aureus, particularly in the N- and C-termini.

DNA Macroarray for Identification and Typing of Staphylococcus aureus Isolates

“…However, when only the 11 genes encoding putative adhesins were taken into account, the higher prevalence of sdrD in BI isolates than in NC isolates became significant. Some SD proteins were shown to bind fibrinogen (ClfA [21], ClfB [25], and SdrG [16]) or bone sialoprotein (Bbp) (33), but the ability of SdrD to bind a matrix protein(s) has not been investigated. The impact of sdrD inactivation merits evaluation in an animal model of BIs.…”

Staphylococcus aureus clumping factor B mediates biofilm formation in the absence of calcium

“…The N-terminal A domain mediates fibrinogen binding and subsequently can lead to bacterial adherence to immobilized fibrinogen, blood clots, conditioned biomaterial ex vivo and thrombin-damaged heart valves in a rat model of infective endocarditis (Entenza et al, 2000;François et al, 2000;McDevitt et al, 1994;Ní Eidhin et al, 1998;O'Brien et al, 2002;Vaudaux et al, 1995). The A domain of ClfB contains a short SLAVA motif, which is a putative protease recognition sequence (McDevitt et al, 1994). The A region also appears to contain an abbreviated EF-Hand domain (Ní Eidhin et al, 1998).…”

“…ClfB is a 150 kDa protein with a C-terminal LPXTG sorting motif, which is used to covalently anchor the MSCRAMM (microbial surface component recognizing adhesive matrix molecule) to the cell wall peptidoglycan (Schneewind et al, 1993). The N-terminal A domain mediates fibrinogen binding and subsequently can lead to bacterial adherence to immobilized fibrinogen, blood clots, conditioned biomaterial ex vivo and thrombin-damaged heart valves in a rat model of infective endocarditis (Entenza et al, 2000;François et al, 2000;McDevitt et al, 1994;Ní Eidhin et al, 1998;O'Brien et al, 2002;Vaudaux et al, 1995). The A domain of ClfB contains a short SLAVA motif, which is a putative protease recognition sequence (McDevitt et al, 1994).…”

Host Airway Proteins Interact withStaphylococcus aureusduring Early Pneumonia

“…In addition, protein A associates with von Willebrand factor and tumor necrosis factor alpha receptor 1 (TNFR1) (10,12,16,25). Several S. aureus proteins have been shown to interact with fibrinogen and plasminogen, which are components of the coagulation cascade (32,35,37,46).…”