Enterococcal Leucine-Rich Repeat-Containing Protein Involved in Virulence and Host Inflammatory Response

Brinster, Sophie; Posteraro, Brunella; Bierne, Hélène; Alberti, Adriana; Makhzami, Samira; Serror, Pascale

doi:10.1128/iai.00279-07

Cited by 49 publications

(90 citation statements)

References 72 publications

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“…These observations may be correlated with the reduced ability of the ⌬ace mutant to survive within macrophages in comparison to that of the wild type. Similar results have been observed with ElrA and aggregation substance, other surface proteins of E. faecalis involved in the virulence process and intramacrophage survival (2,7). In addition, ⌬ace mutant strain bacterial counts recovered from macrophages at 8 h postinfection were reduced compared to those of the wild type.…”

Section: Discussionsupporting

confidence: 74%

ace , Which Encodes an Adhesin in Enterococcus faecalis , Is Regulated by Ers and Is Involved in Virulence

Lebreton

Riboulet-Bisson

Serror³

et al. 2009

Infect Immun

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103

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Enterococcus faecalis is an opportunistic pathogen that causes numerous infectious diseases in humans and is a major agent of nosocomial infections. In this work, we showed that the recently identified transcriptional regulator Ers (PrfA like), known to be involved in the cellular metabolism and the virulence of E. faecalis, acts as a repressor of ace, which encodes a collagen-binding protein. We characterized the promoter region of ace, and transcriptional analysis by reverse transcription-quantitative PCR and mobility shift protein-DNA binding assays revealed that Ers directly regulates the expression of ace. Transcription of ace appeared to be induced by the presence of bile salts, probably via the deregulation of ers. Moreover, with an ace deletion mutant and the complemented strain and by using an insect (Galleria mellonella) virulence model, as well as in vivo-in vitro murine macrophage models, we demonstrated for the first time that Ace can be considered a virulence factor for E. faecalis. Furthermore, animal experiments revealed that Ace is also involved in urinary tract infection by E. faecalis.Enterococcus faecalis is a natural member of the intestinal microflora of warm-blooded animals and humans. However, E. faecalis remains an important opportunistic pathogen and represents one of the principal causes of nosocomial infections in the United States and Europe (33; for a review, see reference 20). Especially for immunocompromised patients, these infections include endocarditis, meningitis, pneumonia, peritonitis, visceral abscesses, urinary infections, and septicemia (13). About a dozen putative virulence factors have been identified in E. faecalis, but mechanisms of virulence remain not fully understood. These factors are involved in different steps of the infection process, such as attachment to host cells or extracellular matrix (ECM), macrophage resistance, tissue damage, and immune system evasion (20).For extracellular pathogens such as E. faecalis or Staphylococcus aureus, components of ECM or serum (i.e., collagen, fibronectin, and fibrinogen) are preferred targets for adhesion. During important steps of the infectious process, they interact with bacterial surface-exposed molecules, which include microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). Ace, an adhesin that binds collagen (types I and IV) and laminin and belongs to the MSCRAMM family, was identified in E. faecalis by sequence homology with the virulence factor Cna, a well-characterized MSCRAMM in S. aureus (16,26). Synthesis of the A domain of Ace by S. aureus increased its arthritogenic potential to a level similar to that of S. aureus expressing Cna (34). Study of the sequence diversity of ace among several strains of E. faecalis has revealed an important variation in the number of repeated sequences (17). However, the role played by these regions has not yet been elucidated. The expression of Ace is significantly induced by high temperature (culture at 46°C) and in vivo by the presence of serum or ECM com...

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Section: Discussionsupporting

confidence: 74%

ace , Which Encodes an Adhesin in Enterococcus faecalis , Is Regulated by Ers and Is Involved in Virulence

Lebreton

Riboulet-Bisson

Serror³

et al. 2009

Infect Immun

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103

116

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“…This work was corroborated by Brinster et al when E. faecalis WxL domain recombinant protein fusions were shown to bind other Gram-positive bacteria, and experiments indicated peptidoglycan as the binding ligand (4). Moreover, Brinster et al also deleted one of the 27 WxL genes in E. faecalis V583 encoding an internalin-like protein (ElrA), which led to significant attenuation in a mouse peritonitis model and reduced bacterial dissemination to the spleen, liver, and host macrophages (9). However, it is unclear if the involvement of elrA in virulence is associated with WxL proteins in general, or if this observation was specific for the ElrA protein.…”

supporting

confidence: 61%

“…In silico analysis determined that these are in three clusters flanked by predicted rho-independent terminators in each genome, resembling the pattern found in E. faecalis and L. plantarum clusters (Fig. 1) (7,9). All three clusters (named WxL loci A, B, and C) encode proteins which can be divided into 3 different classes based on size, domains, and motif characteristics described previously (7): (i) a small WxL protein (SwpA-C), analogous to CscB in Lactobacillus plantarum; (ii) a large WxL protein (LwpA-C), analogous to CscC; and (iii) a DUF916 (domain of unknown function) family protein (DufA-C), analogous to CscA (7).…”

Section: Resultsmentioning

confidence: 99%

The Identification and Functional Characterization of WxL Proteins from Enterococcus faecium Reveal Surface Proteins Involved in Extracellular Matrix Interactions

Galloway-Peña

Liang²,

Singh

et al. 2015

J Bacteriol

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fThe WxL domain recently has been identified as a novel cell wall binding domain found in numerous predicted proteins within multiple Gram-positive bacterial species. However, little is known about the function of proteins containing this novel domain. Here, we identify and characterize 6 Enterococcus faecium proteins containing the WxL domain which, by reverse transcription-PCR (RT-PCR) and genomic analyses, are located in three similarly organized operons, deemed WxL loci A, B, and C. Western blotting, electron microscopy, and enzyme-linked immunosorbent assays (ELISAs) determined that genes of WxL loci A and C encode antigenic, cell surface proteins exposed at higher levels in clinical isolates than in commensal isolates. Secondary structural analyses of locus A recombinant WxL domain-containing proteins found they are rich in ␤-sheet structure and disordered segments. Using Biacore analyses, we discovered that recombinant WxL proteins from locus A bind human extracellular matrix proteins, specifically type I collagen and fibronectin. Proteins encoded by locus A also were found to bind to each other, suggesting a novel cell surface complex. Furthermore, bile salt survival assays and animal models using a mutant from which all three WxL loci were deleted revealed the involvement of WxL operons in bile salt stress and endocarditis pathogenesis. In summary, these studies extend our understanding of proteins containing the WxL domain and their potential impact on colonization and virulence in E. faecium and possibly other Gram-positive bacterial species. Enterococcus faecium is one of the "no ESKAPE" pathogens responsible for a considerable percentage of nosocomial infections; its ability to cause life-threatening infections and resistance to antibiotics cause considerable difficulties for patients and physicians (1). To date, many of the potential virulence determinants that have been described in E. faecium are MSCRAMMs (microbial surface components recognizing adhesive matrix molecules); these include adhesins or pili anchored to the cell surface by an LPxTG-like motif and contain IgG-like folds (2). Our group previously performed a bioinformatic search for novel surface proteins that might be virulence factors in the E. faecium endocarditis strain TX16 (also known as DO) (3). During this search, we identified a locus which included predicted proteins possessing the previously described WxL domain colocated with a predicted LPxTG-like protein (Fms6) (3, 4).The WxL domain is comprised of several conserved residues along with a highly conserved YXXX(L/I/V)TWXLXXXP motif and a second WxL proximal motif in the last ϳ120 to 190 C-terminal residues of a protein (4,5). Genes encoding proteins with the WxL domain were first described in Lactobacillus plantarum as part of a novel gene cluster found in a subset of low-GϩC-content Gram-positive bacterial species, one of which is E. faecium (6, 7). Bioinformatics and transcriptome data in L. plantarum predicted these loci form cell surface protein complexes involved in ca...

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“…In a similar study using a wild type E. faecalis strain OG1RF and its isogenic ElrA-deficient mutant, a role for ElrA in E. faecalis-mediated IL-6 induction was established. 16 In this study, although other time points were not evaluated, the level of IL-6 at 20 h post-infection was at least twofold lower in mice infected with an ElrA-deficient mutant compared with the parent strain, OG1RF. Interestingly, no differences were observed in the expression of a number of other cytokines, including TNF-a and IL-1b.…”

Section: Discussionmentioning

confidence: 99%

“…Enterococcal aggregation substance and binding substance have been implicated in the stimulation of an inflammatory response in vitro, 15 and, more recently, enterococcal leucine-rich repeat-containing protein (ElrA) has been shown to stimulate host inflammation and contribute to E. faecalis virulence. 16 Enterococcal surface protein (Esp) was identified initially as a surface protein in a highly virulent, gentamicin-resistant E. faecalis isolate from a bacteremia. 17 The esp gene is found to be enriched in infection-derived E. faecalis isolates and an esp homolog is present in E. faecium isolates.…”

Section: Introductionmentioning

confidence: 99%

Surface protein Esp enhances pro-inflammatory cytokine expression through NF-κB activation during enterococcal infection

Zou

Shankar

2015

Innate Immun

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Enterococcal surface protein (Esp) is encoded on a pathogenicity island in Enterococcus faecalis and E. faecium and is involved in biofilm formation and binding to epithelial cells. In this study, using Esp-expressing E. faecalis MMH594 and its isogenic Esp-deficient strain, as well as purified Esp, we show that Esp is sufficient for activation of NF-kB and the subsequent production of pro-inflammatory cytokines IL-1b and TNF-a in macrophages in vitro. In a mouse peritonitis model, we also show that mice infected with Esp-expressing E. faecalis showed comparatively higher levels of cytokines TNF-a, IL-1b and IL-6 in peritoneal fluid, and IL-6 in serum. Moreover, neutrophil infiltration and tissue damage in the liver was higher in the mice infected with the Esp-expressing strain compared with mice infected with the Esp-deficient mutant. These results add Esp to the growing list of enterococcal virulence factors that can modulate inflammation during infection and has implications for enterococcal pathogenesis.

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Enterococcal Leucine-Rich Repeat-Containing Protein Involved in Virulence and Host Inflammatory Response

Cited by 49 publications

References 72 publications

ace , Which Encodes an Adhesin in Enterococcus faecalis , Is Regulated by Ers and Is Involved in Virulence

ace , Which Encodes an Adhesin in Enterococcus faecalis , Is Regulated by Ers and Is Involved in Virulence

The Identification and Functional Characterization of WxL Proteins from Enterococcus faecium Reveal Surface Proteins Involved in Extracellular Matrix Interactions

Surface protein Esp enhances pro-inflammatory cytokine expression through NF-κB activation during enterococcal infection

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