Aggregation substance-mediated adherence of Enterococcus faecalis to immobilized extracellular matrix proteins

Rozdzinski, Eva; Marre, R.; Šuša, Milorad; Wirth, Reinhard; Muscholl-Silberhorn, Albrecht

doi:10.1006/mpat.2000.0429

Cited by 82 publications

(59 citation statements)

References 63 publications

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“…Recently, it was reported that AS promotes the adhesion of E. faecalis to fibrin (24) as well as to the extracellular matrix proteins fibronectin, vitronectin, collagen type I, and thrombospondin (36). In direct interaction with cultured mammalial cells, AS-mediated uptake was demonstrated with intestinal epithelial cells (34,43) and a colon cell line (26).…”

Section: Discussionmentioning

confidence: 99%

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In Vivo Induction of Virulence and Antibiotic Resistance Transfer in Enterococcus faecalis Mediated by the Sex Pheromone-Sensing System of pCF10

2002

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Enterococcus faecalis has become one of the most notable nosocomial pathogens in the last decade. Aggregation substance (AS) on the sex pheromone plasmids of E. faecalis has been implicated as a virulence factor in several model systems. We investigated the AS-encoding plasmid pCF10 for its ability to increase virulence in a rabbit endocarditis model. Cells containing pCF10 increased the virulence in the model significantly, as assessed by an increase in aortic valve vegetation size. The results confirmed in vivo induction of the normally tightly controlled AS. In addition to the expression of AS when E. faecalis cells were in contact with plasma, plasmid transfer of the tetracycline resistance-carrying plasmid was also activated in vitro and in vivo. In vivo, plasmid transfer reached remarkable frequencies of 8 ؋ 10 ؊2 to 9 ؋ 10 ؊2 . These values are comparable to the highest frequencies ever observed in vitro. Cells harboring pCF10 had a significant survival advantage over plasmid-free cells indicated by pCF10 present in two-thirds of the recipient population. Plasma induction was dependent on the presence of the plasmid-encoded PrgZ protein, indicating the requirement of the pheromonesensing system in the induction process. The data suggested that the mechanism of in vivo induction may involve interference of plasma with the normal function of the pheromone peptide and its inhibitor. Aggregation substance (AS) is a 137-kDa surface protein encoded on sex pheromone plasmids of Enterococcus faecalis.This protein mediates strong binding between E. faecalis cells as manifested by the formation of visible cell aggregates preceding the conjugative transfer of a sex pheromone plasmid (14). The plasmid transfer response is initiated by 7-to 8-amino-acid-long hydrophobic peptides secreted by potential recipient cells (16,32). These peptides are part of signal sequences of chromosomally encoded lipoproteins (10) and lead to induction of AS expression.Asc10, the AS of the sex pheromone plasmid pCF10 (encoding tetracycline resistance) (17), is induced by the 7-aminoacid peptide cCF10 (32) encoded by the ccfA gene. The donor cell binds the peptide (37), employing a specific plasmid-encoded receptor, PrgZ, an OppA homologue (Fig. 1). The peptide is then transported into the cell via the oligopeptide permease system (29), leading to the expression of AS and subsequent plasmid transfer. Since expression of AS and the other plasmid transfer machinery is presumably a very energyconsuming process, it is not surprising that expression of AS is tightly regulated. This ensures that the nonmotile enterococcal cells expressing transfer functions are in close proximity for cell contact to occur between mating partners. pCF10 donor cells are faced with the dilemma that they secrete unaltered amounts of cCF10 (33), necessitating a complex scheme to prevent autoinduction by their own pheromones. A schematic overview of the events controlling AS expression is given in Fig. 1. Secreted cCF10 may accumulate to approximately 8 pg/ml (33). To...

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Section: Discussionmentioning

confidence: 99%

“…Studies demonstrating AS involvement in virulence were performed with mostly constitutive AS-expressing cells in both the pAD1 and pCF10 systems (26,28,(34)(35)(36)38). The tight regulation of AS expression in vitro led us to investigate if AS on the plasmid pCF10 plays a role in a rabbit endocarditis model and therefore if AS on pCF10 is induced in vivo.…”

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confidence: 99%

In Vivo Induction of Virulence and Antibiotic Resistance Transfer in Enterococcus faecalis Mediated by the Sex Pheromone-Sensing System of pCF10

2002

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“…To investigate the adhesion of S. agalactiae to immobilized ECM components, adherence assays were performed in ECM-coated Terasaki plates as published (25). To investigate fibrinogen adhesion, 60-well Terasaki plates were incubated for 18 h with human fibrinogen (Sigma) reconstituted in Dulbecco's phosphate-buffered saline (DPBS).…”

Section: Methodsmentioning

confidence: 99%

rgf Encodes a Novel Two-Component Signal Transduction System of Streptococcus agalactiae

et al. 2002

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The adhesion of gram-positive bacteria to extracellular matrix (ECM) proteins is regarded as an important determinant of pathogenicity. A comparison of the adhesion of Streptococcus agalactiae strain O90R to different ECM proteins showed that the most pronounced binding could be observed for immobilized fibrinogen. To investigate the genetic determinants of S. agalactiae fibrinogen binding, a pGhost9:ISS1 mutant library was screened for mutants displaying reduced agglutination of fibrinogen-coated latex beads. A putative two-component signal transduction system was identified and designated rgfBDAC. It comprises genes encoding a putative response regulator of 218 amino acids and a putative histidine kinase of 426 amino acids. Comparison of the deduced proteins with the GenBank database revealed a significant similarity to quorum-sensing systems of gram-positive pathogens. Transcription analysis of the rgf locus showed that the encoding genes are located on one transcript. To further characterize the influence of the putative histidine kinase encoded in the rgf locus on the adhesion of S. agalactiae to immobilized fibrinogen, a targeted mutant of rgfC was generated. In comparison to the wild-type strain this mutant demonstrated altered fibrinogen binding capacities depending on bacterial cell density. Transcription analysis of secreted and surface-localized S. agalactiae proteins in the wild type and the rgfC mutant strain revealed that mRNA levels of the C5a peptidase gene scpB were increased in the mutant strain while the transcription of the secreted CAMP factor gene cfb was unaffected by this mutation. Based on these results, we hypothesize that rgf regulates the expression of bacterial cell surface components.Streptococcus agalactiae (group B streptococcus) is an important human pathogen causing neonatal pneumonia, sepsis, and meningitis and severe infections in immunocompromised adult patients. It has the ability to survive and multiply in various host compartments requiring the expression and coordinate regulation of multiple pathogenicity factors. Several group B streptococcal molecules important for pathogenicity and virulence have been identified and characterized. However, the regulation and control of these factors are poorly understood, and a typical two-component regulatory system that controls their expression has not yet been described.In gram-positive bacteria, peptide-based signal transduction appears to be the preferred mechanism to sense and respond to population density and coordinate the expression of molecules that are important for pathogenicity. A comprehensive review of bacterial quorum sensing has been published recently (6). Peptide-controlled two-component signal transduction systems regulate the production of pathogenicity factors in Staphylococcus aureus (20), competence of streptococci (10), and bacteriocin production in lactic acid bacteria (7). The agrBDCA (accessory gene regulator) locus encodes the quorum-sensing system that controls the expression of S. aureus virulence factor...

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“…Gelatinase encoded by gelE gene is an extracellular zinc metalloprotease that hydrolyses gelatine, collagen, casein, haemoglobin, and antimicrobial peptides of the innate immune system (24,25). The asa1 is encoded by pheromoneresponsive plasmids, which often harbour antibiotic resistance genes (26,27). The protein causes clumping of E. faecalis cells and survival inside polymorphonuclear leucocytes, internalisation by intestinal cells, and increases in bacterial binding to cultured renal epithelial cells (28,29).…”

Section: Introductionmentioning

confidence: 99%

Virulence Factor and Biofilm Formation in Clinical Enterococcal Isolates of the West of Iran

Azizi¹,

Banafshe²,

Kashef³

et al. 2017

Jundishapur J Microbiol

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Background: Enterococcus spp., a part of the normal flora of the human intestine, possess several virulence factors that can develop biofilms to endure harsh environments. Their ability to cause nosocomial infections makes them as critical opportunistic pathogens in hospital settings. Objectives: The current study aimed at determining the occurrence of 6 genes coding virulence factors and their ability to develop biofilms, and conducting phenotypical assessments of haemolysin and gelatinase in clinical enterococci isolated from the West of Iran. Methods: A total of 126 isolates were screened for harbouring the following genes: aggregation substance (asa1), cytolysin (cylABM), enterococcal surface protein (esp), and gelatinase (gelE). Isolates were tested for haemolysin and gelatinase expression phenotypically and for biofilm production quantitatively, using the microtiter method.Results: Of the 126 tested isolates, 95 (73%) were Enterococcus faecalis and 28 (21%) were E. faecium. The total frequency of virulence gene was cylA 92 (73%), cylB 85 (67%), cylM 57 (45%), asa1 26 (21%), gelE 64 (51%), and esp 66 (53%); while 98 (75%) of the isolates were able to form biofilm. A total of 74 (58%) and 46 (35%) isolates could secret haemolysin and gelatinase. Conclusions: There was a significant difference between the frequency of virulence gene in E. faecalis and E. faecium. Enterococcus faecium isolates lacked the gelE and asa1 genes and the frequency of cylABM genes were lower than that of E. faecalis isolates. Enterococcus faecalis isolates were relatively rich in virulence factors; no association was observed between biofilm formation and the presence of specific virulence genes.

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Aggregation substance-mediated adherence of Enterococcus faecalis to immobilized extracellular matrix proteins

Cited by 82 publications

References 63 publications

In Vivo Induction of Virulence and Antibiotic Resistance Transfer in Enterococcus faecalis Mediated by the Sex Pheromone-Sensing System of pCF10

In Vivo Induction of Virulence and Antibiotic Resistance Transfer in Enterococcus faecalis Mediated by the Sex Pheromone-Sensing System of pCF10

rgf Encodes a Novel Two-Component Signal Transduction System of Streptococcus agalactiae

Virulence Factor and Biofilm Formation in Clinical Enterococcal Isolates of the West of Iran

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