The capsular polysaccharide of Enterococcus faecalis and its relationship to other polysaccharides in the cell wall

Abstract

With the goal of identifying and characterizing traits of Enterococcus faecalis that play key roles in human disease, we identified an operon specifying synthesis of a capsular carbohydrate of the type most commonly expressed by clinical isolates. This surfaceexposed carbohydrate consists of glycerol phosphate, glucose, and galactose residues, and its biosynthesis is encoded by a determinant that includes 11 ORFs. Insertional inactivation of genes in this pathway yielded mutants with enhanced susceptibility to phagocytic killing in vitro and compromised in the ability to persist in regional lymph nodes in vivo.

Translocation of Enterococcus faecalis Strains across a Monolayer of Polarized Human Enterocyte-Like T84 Cells

“…The epa gene cluster has been shown to be widespread among E. faecalis strains (20), and Epa is thought to be a species-specific polysaccharide (7). While we have not characterized Epa biochemically, Hancock and Gilmore were able to detect three different cell wall carbohydrates in E. faecalis: a type-specific capsular polysaccharide, a rhamnopolysaccharide (possibly Epa), and a polymer likely representing an integral cell wall teichoic acid (7). Their model, in agreement with our earlier observations (27), suggests that the Epa polysaccharide is not on the cell surface, at least in vitro; however, Epa may be important for the overall integrity of membrane and/or cell wall structures, or conceivably, it could be exposed on the surface in vivo.…”

“…1B) and that is important for virulence in mice and for resistance to phagocytosis and/or killing by polymorphonuclear leukocytes (7,20,(25)(26)(27). The epa gene cluster has been shown to be widespread among E. faecalis strains (20), and Epa is thought to be a species-specific polysaccharide (7).…”

The prolipoprotein diacylglyceryl transferase (Lgt) of Enterococcus faecalis contributes to virulence

“…According to Machata et al (2008), L. monocytogenes entry into and survival inside epithelial cells or macrophages can be affected in the absence of Lgt, and there is certainly a balance between adhesion, cytotoxicity, activation of the immune system and lipidation of lipoproteins. Of the 90 predicted lipoproteins in E. faecalis, two [EF1818 (GelE) and EF2076 (EfaA)] are involved in virulence (Qin et al, 2000;Singh et al, 1998), one (EF2488) is encoded by a gene which is a part of an operon responsible for the synthesis of a capsular carbohydrate also involved in virulence (Hancock & Gilmore, 2002), and 39 correspond to putative components of ABC transporters, among which 24 have been predicted to be important for virulence (Reffuveille et al, 2011). Indeed, metal transport is a prerequisite for growth during infection and virulence, and amino acid, peptide and amine ABC transporters, as well as pheromone-binding proteins, could have direct or indirect roles in virulence (Reffuveille et al, 2011).…”

Cold-shock RNA-binding protein CspR is also exposed to the surface of Enterococcus faecalis

“…Therefore, the virulence of E. faecalis has been intensively studied over the past 20 years and~12 putative virulence genes have been reported, including several transcriptional and post-transcriptional regulators. The recently identified cold-shock RNA-binding protein CspR is part of this last category of virulence-associated factors (Fox et al, 2009;Hancock & Gilmore, 2002;Lebreton et al, 2009;Michaux et al, 2011 Michaux et al, , 2012Qin et al, 2001; Shankar et al, 2001). In some Gram-positive bacteria such as Staphylococcus aureus and Bacillus subtilis, cold-shock polypeptides have been shown to be involved in several aspects of bacterial life, i.e.…”