scholarly journals Mechanism for Sortase Localization and the Role of Sortase Localization in Efficient Pilus Assembly in Enterococcus faecalis

2009 ◽  
Vol 191 (10) ◽  
pp. 3237-3247 ◽  
Author(s):  
Kimberly A. Kline ◽  
Andrew L. Kau ◽  
Swaine L. Chen ◽  
Adeline Lim ◽  
Jerome S. Pinkner ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Transmembrane Helix ◽  
Spatial Relationship ◽  
Sortase A ◽  
Aggregation Substance ◽  
Retention Signal ◽  
Positively Charged ◽  
Pilus Assembly

ABSTRACT Pathogenic streptococci and enterococci primarily rely on the conserved secretory (Sec) pathway for the translocation and secretion of virulence factors out of the cell. Since many secreted virulence factors in gram-positive organisms are subsequently attached to the bacterial cell surface via sortase enzymes, we sought to investigate the spatial relationship between secretion and cell wall attachment in Enterococcus faecalis. We discovered that sortase A (SrtA) and sortase C (SrtC) are colocalized with SecA at single foci in the enterococcus. The SrtA-processed substrate aggregation substance accumulated in single foci when SrtA was deleted, implying a single site of secretion for these proteins. Furthermore, in the absence of the pilus-polymerizing SrtC, pilin subunits also accumulate in single foci. Proteins that localized to single foci in E. faecalis were found to share a positively charged domain flanking a transmembrane helix. Mutation or deletion of this domain in SrtC abolished both its retention at single foci and its function in efficient pilus assembly. We conclude that this positively charged domain can act as a localization retention signal for the focal compartmentalization of membrane proteins.

scholarly journals Disparate Findings on the Role of Virulence Factors of Enterococcus faecalis in Mouse and Rat Models of Peritonitis

1998 ◽  
Vol 66 (6) ◽  
pp. 2570-2575 ◽  
Author(s):  
Herve Dupont ◽  
Philippe Montravers ◽  
Jacqueline Mohler ◽  
Claude Carbon
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Lethal Dose ◽  
Systemic Infection ◽  
Rank Test ◽  
Mice Model ◽  
Aggregation Substance ◽  
Log Rank Test ◽  
Monomicrobial Infection

ABSTRACT The role of Enterococcus faecalis in polymicrobial peritonitis is still debated. Virulence factors expressed in some enterococcal strains might be involved in the pathogenicity of these organisms. To clarify their role, three of these virulence factors (cytolysin, gelatinase, and aggregation substance) were studied in six isogenic strains of E. faecalis expressing various combinations of these factors. Since the pathogenic effects of enterococci are only moderate, the expression of their virulence might vary from one animal species to another and from one type of infection to another. Therefore, we evaluated these effects in two animal models, i.e., a systemic infection in mice in which we assessed the virulence of the strains in 50% lethal dose studies and a model of compartmentalized infection in rats in which the microbiologic and inflammatory effects of the strains were evaluated in monomicrobial or polymicrobial infection. In mice, significant differences were observed in the cumulative survival curves depending on the virulence factors (P < 0.0001 [log rank test]). In rats, monomicrobial infection induced only mild changes. In polymicrobial peritonitis, the virulence factors mainly increased the inflammatory response while the changes observed in the microbiologic response were minimal. The combination of two virulence factors did not significantly increase the severity of infection either in the mice model or the polymicrobial rat model. These data argue for species and model dependence of the role of the virulence factors studied here and suggest that other important factors may be involved in the pathogenicity of enterococci.

scholarly journals Enterococcus faecalis Localization in Experimental Endophthalmitis: Role of Plasmid-Encoded Aggregation Substance

1998 ◽  
Vol 66 (2) ◽  
pp. 843-848 ◽  
Author(s):  
Bradley D. Jett ◽  
Rajeshwari V. Atkuri ◽  
Michael S. Gilmore
Keyword(s):  
Nosocomial Infection ◽  
Enterococcus Faecalis ◽  
Direct Observation ◽  
Infection Model ◽  
Organ Function ◽  
Severity Of Disease ◽  
Aggregation Substance ◽  
Mammalian Tissues

ABSTRACT Enterococci have emerged as leading agents of nosocomial infection, yet relatively little is known about the pathogenesis of enterococcal disease. In previous studies, we developed an Enterococcus faecalis endophthalmitis infection model which provides unique opportunities to study the evolution of enterococcal disease by direct observation, as well as through sensitive electrophysiologic measures of organ function. The present study was designed to determine whetherE. faecalis possesses traits that permit its attachment to mammalian tissues during infection. It was also of interest to determine whether a plasmid-encoded adhesin, aggregation substance, contributes to enterococcal localization or otherwise mediates adherence to alternate sites. These studies found that, in this model, enterococci attach to membranous structures occurring within the vitreous but that this attachment or the course or severity of disease is unaffected by the aggregation substance phenotype.

scholarly journals Evaluation of the Effect of MTAD on Expression of Enterococcus faecalis Virulence Factors Considering the Role of Different Obturating Materials

2019 ◽  
Author(s):  
Behnam Bolhari ◽  
Abbas Bahador ◽  
Mehrfam Khoshkhounejad ◽  
Mahsa Sobhi Afshar ◽  
Mohammad Moghaddaszadeh
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Root Canal ◽  
Statistical Power ◽  
P Value ◽  
Human Teeth ◽  
Root Canals ◽  
Gutta Percha ◽  
Post Hoc

Objectives: The aim of this study was to determine the effect of MTAD on the expression of virulence factors of Enterococcus faecalis (E.faecalis) considering the role of Gutta-percha/AH26 or Resilon/RealSeal SE as root canal obturating materials. Materials and Methods: One-hundred and forty-four single-rooted human teeth were instrumented to a standardized apical size. Root canals were infected by E.faecalis (ATCC 29212). Ninety teeth were irrigated with MTAD and randomly divided into three groups. In two groups, root canals were obturated by either Gutta-percha/AH26 or Resilon/RealSeal SE. Root canals were kept unobturated in the third group. The remaining 54 teeth received no final irrigation. All groups were then subdivided into three timepoint subgroups in which dentin powder was obtained from each sample to determine the expression of specific virulence factors of E.faecalis (efa, esp, gel, fsr) using real-time reverse transcription polymerase chain reaction (RT-PCR). Statistical analysis was performed by one-way analysis of variance (ANOVA) and Tukey’s post-hoc test. The statistical power was set at P-value ≤0.05. Results: MTAD was effective against the expression of most of the tested virulence factors, and Gutta-percha/AH26 increased the antibacterial efficacy of MTAD. Conclusions: MTAD could inhibit the expression of some known virulence factors of E.faecalis at the majority of tested timepoints. This may partly explain some of the mechanisms of antimicrobial efficacy of MTAD against this resistant microorganism which is known as one of the main causes of failure of root canal treatment.

scholarly journals Role of the Enterococcus faecalis GelE Protease in Determination of Cellular Chain Length, Supernatant Pheromone Levels, and Degradation of Fibrin and Misfolded Surface Proteins

2003 ◽  
Vol 185 (12) ◽  
pp. 3613-3623 ◽  
Author(s):  
Christopher M. Waters ◽  
Michelle H. Antiporta ◽  
Barbara E. Murray ◽  
Gary M. Dunny
Keyword(s):  
Chain Length ◽  
Enterococcus Faecalis ◽  
Epidemiological Data ◽  
Surface Proteins ◽  
Mutant Proteins ◽  
Model Studies ◽  
Aggregation Substance ◽  
Peptide Pheromone

ABSTRACT Gelatinase (GelE), a secreted Zn-metalloprotease of Enterococcus faecalis, has been implicated as a virulence factor by both epidemiological data and animal model studies. Expression of gelE is induced at a high cell density by the fsr quorum-sensing system. In the present study, GelE was shown to be responsible for the instability of a number of Asc10 (aggregation substance) mutant proteins, implying that GelE functions to clear the bacterial cell surface of misfolded proteins. Disruption of GelE production led to increased cell chain length of E. faecalis, from a typical diplococcus morphology to chains of 5 to 10 cells. This function of GelE was also exhibited when the protein was expressed in Streptococcus pyogenes. GelE-expressing E. faecalis strains were more autolytic, suggesting that GelE affects chain length through activation of an autolysin. GelE was also essential for degradation of polymerized fibrin. GelE expression reduced the titer of cCF10, the peptide pheromone that induces conjugation of pCF10, and pCF10 had increased conjugation into non-GelE-expressing strains. These new functions attributed to GelE suggest that it acts to increase the dissemination of E. faecalis in high-density environments.

scholarly journals ENTEROCOCCUS FAECALIS CAN SURVIVE EXTREME CHALLENGES - OVERVIEW

2012 ◽  
Vol 02 (03) ◽  
pp. 49-53
Author(s):  
Rahul Halkai ◽  
Mithra N. Hegde ◽  
Kiran Halkai
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Lipoteichoic Acid ◽  
Lytic Enzymes ◽  
Root Canals ◽  
Aggregation Substance ◽  
Endodontic Infection ◽  
Life Threatening ◽  
Brain Abscesses ◽  
Surface Adhesins

AbstractEnterococcus faecalis is a micro-organism that can survive extreme challenges. Its pathogenicity ranges from life-threatening diseases in compromised individuals to less severe conditions, systemic diseases such as endocarditis, brain abscesses, and septicaemia to infection of obturated root canals with chronic apical periodontitis. This article highlights some of the virulence factors of E. faecalis that may be related to endodontic infections and the periradicular inflammatory response. The most-cited virulence factors are aggregation substance, surface adhesins, sex pheromones, lipoteichoic acid, extracellular superoxide production, the lytic enzymes gelatinase and hyaluronidase, and the toxin cytolysin. Each of them may be associated with various stages of an endodontic infection as well as with periapical inflammation. While some products of the bacterium may be directly linked to damage of the periradicular tissues, a large part of the tissue damage is probably mediated by the host response to the bacterium and its products.

Functional roles of cationic amino acid residues in the sodium-dicarboxylate cotransporter 3 (NaDC-3) from winter flounder

2006 ◽  
Vol 291 (6) ◽  
pp. F1224-F1231 ◽  
Author(s):  
Yohannes Hagos ◽  
Jürgen Steffgen ◽  
Ahsan N. Rizwan ◽  
Denis Langheit ◽  
Ariane Knoll ◽  
...  
Keyword(s):  
Amino Acid ◽  
Transmembrane Helix ◽  
Site Directed Mutagenesis ◽  
Amino Acid Residues ◽  
Cationic Amino Acid ◽  
Functional Roles ◽  
Inward Currents ◽  
Induced Currents ◽  
Positively Charged

In the present study, we determined the functional role of 15 positively charged amino acid residues at or within 1 of the predicted 11 transmembrane helixes of the flounder renal sodium-dicarboxylate cotransporter fNaDC-3. Using site-directed mutagenesis, histidine (H), lysine (K), and arginine (R) residues of fNaDC-3 were replaced by alanine (A), isoleucine (I), or leucine (L). Most mutants showed sodium-dependent, lithium-inhibitable [14C]succinate uptake and, in two-electrode voltage-clamp (TEVC) experiments, Km and Δ Imax values comparable to wild-type (WT) fNaDC-3. The replacement of R109 and R110 by alanine and isoleucine (RR109/110AI) prevented the expression of fNaDC-3 at the plasma membrane. When the lysines at positions 232 and 235 were replaced by isoleucine (KK232/235II), the transporter was expressed but showed small transport rates and succinate-induced currents. K114I, located within transmembrane helix 4, showed [14C]succinate uptake similar to WT but relatively small inward currents. When K114 was replaced by arginine, glutamic acid (E), or glutamine (Q), all mutants were expressed at the cell surface. In [14C]succinate uptake and TEVC experiments performed simultaneously on the same oocytes, uptake was similar to or higher than WT, whereas succinate-induced currents were either comparable (K114R) to, or considerably smaller (K114E, K114I, K114Q) than, those evoked by WT. These results suggest that a positively charged residue at position 114 is required for electrogenic sodium-dicarboxylate cotransport.

scholarly journals Virulence of Enterococcus faecalis dairy strains in an insect model: the role of fsrB and gelE

Microbiology ◽  
2009 ◽  
Vol 155 (11) ◽  
pp. 3564-3571 ◽  
Author(s):  
Frédéric Gaspar ◽  
Neuza Teixeira ◽  
Lionel Rigottier-Gois ◽  
Paulo Marujo ◽  
Christina Nielsen-LeRoux ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Virulence Factors ◽  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Galleria Mellonella ◽  
Deletion Mutants ◽  
Enterococcus Durans ◽  
Cell Functions ◽  
Negative Phenotype

Despite the existence of various virulence factors in the Enterococcus genus, enterococcal virulence is still a debated issue. A main consideration is the detection of the same virulence genes in strains isolated from nosocomial or community-acquired infections, and from food products. The goal of this study was to evaluate the roles of two well-characterized enterococcal virulence factors, Fsr and gelatinase, in the potential virulence of Enterococcus faecalis food strains. Virulence of unrelated Enterococcus isolates, including dairy strains carrying fsr and gelE operons, was compared in the Galleria mellonella insect model. E. faecalis dairy strains were able to kill larvae and were as virulent as strain OG1RF, one of the most widely used for virulence studies. In contrast, Enterococcus durans and Enterococcus faecium strains were avirulent or poorly virulent for G. mellonella. To evaluate the role of fsrB and gelE in virulence of E. faecalis dairy strains, both genes were deleted independently in two strains. The ΔfsrB and ΔgelE deletion mutants both produced a gelatinase-negative phenotype. Although both mutations significantly attenuated virulence in G. mellonella, the ΔfsrB strains were more strongly attenuated. These results agree with previous findings suggesting the involvement of fsrB in the control of other cell functions relevant to virulence. Our work demonstrates that the presence of functional fsrB, and to a lesser extent gelE, in dairy enterococci should be considered with caution.

The Role of Virulence Factors in the Pathogenicity of Colletotrichum sp.

2017 ◽  
Vol 18 (10) ◽  
Author(s):  
Maria G. Villa-Rivera ◽  
Ulises Conejo-Saucedo ◽  
Alicia Lara-Marquez ◽  
Horacio Cano-Camacho ◽  
Everardo Lopez-Romero ◽  
...  
Keyword(s):  
Virulence Factors

scholarly journals Species-Specific Regulation of TRPM2 by PI(4,5)P2 via the Membrane Interfacial Cavity

2021 ◽  
Vol 22 (9) ◽  
pp. 4637
Author(s):  
Daniel Barth ◽  
Andreas Lückhoff ◽  
Frank J. P. Kühn
Keyword(s):  
Amino Acid Residues ◽  
Hek 293 ◽  
Complete Inactivation ◽  
293 Cells ◽  
Activation Mechanisms ◽  
Specific Regulation ◽  
Species Specific ◽  
Inside Out ◽  
Positively Charged

The human apoptosis channel TRPM2 is stimulated by intracellular ADR-ribose and calcium. Recent studies show pronounced species-specific activation mechanisms. Our aim was to analyse the functional effect of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), commonly referred to as PIP2, on different TRPM2 orthologues. Moreover, we wished to identify the interaction site between TRPM2 and PIP2. We demonstrate a crucial role of PIP2, in the activation of TRPM2 orthologues of man, zebrafish, and sea anemone. Utilizing inside-out patch clamp recordings of HEK-293 cells transfected with TRPM2, differential effects of PIP2 that were dependent on the species variant became apparent. While depletion of PIP2 via polylysine uniformly caused complete inactivation of TRPM2, restoration of channel activity by artificial PIP2 differed widely. Human TRPM2 was the least sensitive species variant, making it the most susceptible one for regulation by changes in intramembranous PIP2 content. Furthermore, mutations of highly conserved positively charged amino acid residues in the membrane interfacial cavity reduced the PIP2 sensitivity in all three TRPM2 orthologues to varying degrees. We conclude that the membrane interfacial cavity acts as a uniform PIP2 binding site of TRPM2, facilitating channel activation in the presence of ADPR and Ca2+ in a species-specific manner.

Sign in / Sign up

Export Citation Format

Share Document