Enterococcus faecalis Adhesin, Ace, Mediates Attachment to Extracellular Matrix Proteins Collagen Type IV and Laminin as well as Collagen Type I

Abstract

Adhesin-mediated binding to extracellular matrix (ECM) proteins is thought to be a crucial step in the pathogenic process of many bacterial infections. We have previously reported conditional adherence of most Enterococcus faecalis isolates, after growth at 46°C, to ECM proteins collagen types I and IV and laminin; identified an E. faecalis-specific gene, ace, whose encoded protein has characteristics of a bacterial adhesin; and implicated Ace in binding to collagen type I. In this study, we constructed an ace disruption mutant from E. faecalis strain OG1RF that showed marked reduction in adherence to collagen types I and IV and laminin when compared to the parental OG1RF strain after growth at 46°C. Polyclonal immune serum raised against the OG1RF-derived recombinant Ace A domain reacted with a single ϳ105-kDa band of mutanolysin extracts from OG1RF grown at 46°C, while no band was detected in extracts from OG1RF grown at 37°C, nor from the OG1RF ace mutant grown at 37 or 46°C. IgGs purified from the anti-Ace A immune serum inhibited adherence of 46°C-grown E. faecalis OG1RF to immobilized collagen type IV and laminin as well as collagen type I, at a concentration as low as 1 g/ml, and also inhibited the 46°C-evoked adherence of two clinical isolates tested. We also showed in vitro interaction of collagen type IV with Ace from OG1RF mutanolysin extracts on a far-Western blot. Binding of recombinant Ace A to immobilized collagen types I and IV and laminin was demonstrated in an enzyme-linked immunosorbent assay and was shown to be concentration dependent. These results indicate that Ace A mediates the conditional binding of E. faecalis OG1RF to collagen type IV and laminin in addition to collagen type I.

A family of putative MSCRAMMs from Enterococcus faecalis

“…In addition to the six novel putative enterococcal MSCRAMM proteins, ACE (EF1099), which can act as a collagen/laminin-binding adhesin (Nallapareddy et al, 2000b;Rich et al, 1999), was also identified in our search and characterized for comparison. We have recently been able to crystallize the A-region of ACE (Ponnuraj et al, 2002).…”

“…ACE, a collagen-binding adhesin of the MSCRAMM (microbial surface component recognizing adhesive matrix molecules) family is an exception. This protein was previously identified in our laboratories based on its sequence similarity to the staphylococcal MSCRAMM CNA (Nallapareddy et al, 2000b;Rich et al, 1999). Both proteins bind to multiple sites in collagen but with different kinetics.…”

Vancomycin-Resistant Enterococcus faecalis Endocarditis: Linezolid Failure and Strain Characterization of Virulence Factors

“…E. faecalis strains recovered from patients with endocarditis have a greater capacity to adhere to Girardi heart cells than to urinary tract epithelial cells in vitro (6), which suggests that adherence to vascular endothelium may be important. MSCRAMMs mediate binding of bacteria to extracellular matrix proteins and function as adhesins to damaged heart tissue (17,18,27). Ace is a specific collagen-binding adhesin of the MSCRAMM family, has been identified in E. faecalis endocarditis isolates (17), and mediates attachment of E. faecalis to collagen types I and IV and laminin (18).…”

“…These included the gelatinase gene (22,26,28,30); recently described pilus-encoding genes (16); genes encoding putative MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) with predicted immunoglobulin (Ig)-like folds (17,18,27; J. Sillanpää, S. R. Nallapareddy, and B. E. Murray, unpublished data); genes, including esp (33), in a predicted pathogenicity island (PAI) (15); and an acquired gene that contributes to biofilm formation (32) ( Table 1). The strain was examined for phenotypic production of gelatinase (22), hemolytic activity on Bacto Tryptic Soy Agar (Becton Dickinson and Company, Sparks, MD) plus 5% human blood agar plates, and biofilm formation (14).…”

“…MSCRAMMs mediate binding of bacteria to extracellular matrix proteins and function as adhesins to damaged heart tissue (17,18,27). Ace is a specific collagen-binding adhesin of the MSCRAMM family, has been identified in E. faecalis endocarditis isolates (17), and mediates attachment of E. faecalis to collagen types I and IV and laminin (18). Subsequently, a family of seven genes encoding MSCRAMM-like proteins was found in 100% (nine out of nine) of the E. faecalis endocarditis strains tested, and elevated titers of IgG to these MSCRAMMlike proteins were found in the sera of nine patients with E. faecalis infections (27).…”