Bactericidal Activity of Carvacrol against Involves Alteration of Membrane Fluidity and Integrity through Interaction with Membrane Phospholipids.

Background: Carvacrol, a mono-terpenoid phenol found in herbs, such as oregano and thyme, has excellent antibacterial properties against . However, its mechanism of bactericidal activity on has not been elucidated.

Objectives: This study investigated the bactericidal mechanism of carvacrol using three strains of .

Carvacrol Suppresses Inflammatory Biomarkers Production by Lipoteichoic Acid- and Peptidoglycan-Stimulated Human Tonsil Epithelial Cells.

Pharyngitis is an inflammation of the pharynx caused by viral, bacterial, or non-infectious factors. In the present study, the anti-inflammatory efficacy of carvacrol was assessed using an in vitro model of streptococcal pharyngitis using human tonsil epithelial cells (HTonEpiCs) induced with cell wall antigens. HTonEpiCs were stimulated by a mixture of lipoteichoic acid (LTA) and peptidoglycan (PGN) for 4 h followed by exposure to carvacrol for 20 h.

Identification of a Thiol-Disulfide Oxidoreductase (SdbA) Catalyzing Disulfide Bond Formation in the Superantigen SpeA in Streptococcus pyogenes.

Mechanisms of disulfide bond formation in the human pathogen Streptococcus pyogenes are currently unknown. To date, no disulfide bond-forming thiol-disulfide oxidoreductase (TDOR) has been described and at least one disulfide bonded protein is known in S. pyogenes.

Carvacrol exhibits rapid bactericidal activity against Streptococcus pyogenes through cell membrane damage.

Streptococcus pyogenes is an important human pathogen worldwide. The identification of natural antibacterial phytochemicals has renewed interest due to the current scarcity of antibiotic development. Carvacrol is a monoterpenoid found in herbs.

The MsrAB reducing pathway of Streptococcus gordonii is needed for oxidative stress tolerance, biofilm formation, and oral colonization in mice.

The ability of Streptococcus gordonii to cope with oxidative stress is important for survival and persistence in dental plaque. In this study, we used mutational, phenotypic, and biochemical approaches to characterize the role of a methionine sulfoxide reductase (MsrAB) and proteins encoded by genes in the msrAB operon and an adjacent operon in oxidative stress tolerance in S. gordonii.

Identification of Redox Partners of the Thiol-Disulfide Oxidoreductase SdbA in Streptococcus gordonii.

We previously identified a novel thiol-disulfide oxidoreductase, SdbA, in that formed disulfide bonds in substrate proteins and played a role in multiple phenotypes. In this study, we used mutational, phenotypic, and biochemical approaches to identify and characterize the redox partners of SdbA. Unexpectedly, the results showed that SdbA has multiple redox partners, forming a complex oxidative protein-folding pathway.

Expression, purification, and functional analysis of an antigen-targeting fusion protein composed of CD40 ligand and the C-terminal fragment of ovalbumin.

Delivering antigen via molecules specifically targeting receptors on the surface of antigen-presenting cells is a strategy to improve immune responses. In this study, an antigen-targeting fusion protein (OVA-CD40LS) composed of the C-terminal fragment of ovalbumin and the extracellular domain of mouse CD40 ligand was constructed by genetic fusion. The OVA-CD40LS and the control OVA (rOVA) genes were cloned in Escherichia coli and over-expressed as insoluble proteins.

Mutation of the Streptococcus gordonii Thiol-Disulfide Oxidoreductase SdbA Leads to Enhanced Biofilm Formation Mediated by the CiaRH Two-Component Signaling System.

Streptococcus gordonii is a commensal inhabitant of human oral biofilms. Previously, we identified an enzyme called SdbA that played an important role in biofilm formation by S. gordonii.

Thiol-Disulfide Exchange in Gram-Positive Firmicutes.

Extracytoplasmic thiol-disulfide oxidoreductases (TDORs) catalyze the oxidation, reduction, and isomerization of protein disulfide bonds. Although these processes have been characterized in Gram-negative bacteria, the majority of Gram-positive TDORs have only recently been discovered. Results from recent studies have revealed distinct trends in the types of TDOR used by different groups of Gram-positive bacteria, and in their biological functions.

Development of a gene delivery system in Streptococcus gordonii using thymidylate synthase as a selection marker.

Streptococcus gordonii, a commensal bacterium of the human oral cavity, is a potential live vaccine vector. In this study, we have developed a system that delivers a vaccine antigen gene onto the chromosome of S. gordonii.

Mutation of the Thiol-Disulfide Oxidoreductase SdbA Activates the CiaRH Two-Component System, Leading to Bacteriocin Expression Shutdown in Streptococcus gordonii.

Unlabelled: Streptococcus gordonii is a commensal inhabitant of the human oral cavity. To maintain its presence as a major component of oral biofilms, S. gordonii secretes inhibitory molecules such as hydrogen peroxide and bacteriocins to inhibit competitors.

The disulfide oxidoreductase SdbA is active in Streptococcus gordonii using a single C-terminal cysteine of the CXXC motif.

Recently, we identified a novel disulfide oxidoreductase, SdbA, in the oral bacterium Streptococcus gordonii. Disulfide oxidoreductases form disulfide bonds in nascent proteins using a CXXC catalytic motif. Typically, the N-terminal cysteine interacts with substrates, whereas the C-terminal cysteine is buried and only reacts with the first cysteine of the motif.

Immunoblotting conditions for small peptides from streptococci.

Streptococci secrete small peptides with important biological functions. These peptides are not amenable to standard immunoblotting, and are often detected indirectly using activity assays, or by alternative approaches that may be expensive and laborious. Here we describe an immunoblotting method that enables reproducible detection of these small streptococcal peptides.

Functional analysis of paralogous thiol-disulfide oxidoreductases in Streptococcus gordonii.

Disulfide bonds are important for the stability of many extracellular proteins, including bacterial virulence factors. Formation of these bonds is catalyzed by thiol-disulfide oxidoreductases (TDORs). Little is known about their formation in Gram-positive bacteria, particularly among facultative anaerobic Firmicutes, such as streptococci.

Isolation and characterization of an antibacterial biflavonoid from an African chewing stick Garcinia kola Heckel (Clusiaceae).

Ethnopharmacological Relevance: The use of African chewing sticks in maintaining oral health is widely practiced in African countries. It has been reported that chewing stick users have a lower rate of dental caries and a better general oral health than non-users. It is generally thought that the beneficial effect of chewing stick is attributed to the mechanical cleansing effect and antimicrobial substances present in the stick.

Role of surface proteins SspA and SspB of Streptococcus gordonii in innate immunity.

Streptococcus gordonii, a normal inhabitant of the human oral cavity, is a potential live vaccine vehicle. Several pathogen-associated molecular patterns from S. gordonii that are recognized by antigen-presenting cells have recently been identified.

Role of the cell wall microenvironment in expression of a heterologous SpaP-S1 fusion protein by Streptococcus gordonii.

The charge density in the cell wall microenvironment of Gram-positive bacteria is believed to influence the expression of heterologous proteins. To test this, the expression of a SpaP-S1 fusion protein, consisting of the surface protein SpaP of Streptococcus mutans and a pertussis toxin S1 fragment, was studied in the live vaccine candidate bacterium Streptococcus gordonii. Results showed that the parent strain PM14 expressed very low levels of SpaP-S1.

Overcoming codon-usage bias in heterologous protein expression in Streptococcus gordonii.

One of the limitations facing the development of Streptococcus gordonii into a successful vaccine vector is the inability of this bacterium to express high levels of heterologous proteins. In the present study, we have identified 12 codons deemed as rare codons in S. gordonii and seven other streptococcal species.

Expression of the Streptococcus mutans essential two-component regulatory system VicRK is pH and growth-phase dependent and controlled by the LiaFSR three-component regulatory system.

As an inhabitant of the human oral cavity, Streptococcus mutans faces frequent environmental changes. Two-component regulatory systems (TCSs) play a critical role in responding to these changes. Recently, an essential TCS, VicRKX, has been identified.

A novel vaccine adjuvant comprised of a synthetic innate defence regulator peptide and CpG oligonucleotide links innate and adaptive immunity.

There has been an increased demand for the development of novel vaccine adjuvants that lead to enhanced induction of protection from infectious challenges and development of immunological memory. A novel vaccine adjuvant was developed comprising a complex containing CpG oligonucleotide and the synthetic cationic innate defence regulator peptide HH2 that has enhanced immune modulating activities. The complex of HH2 and the CpG oligonucleotide 10101 was a potent inducer of cytokine/chemokine expression ex vivo, retained activity following extended storage, had low associated cytotoxicity, and upregulated surface marker expression in dendritic cells, a critical activity for a vaccine adjuvant.

Synergistic BM-DC activation and immune induction by the oral vaccine vector Streptococcus gordonii and exogenous tumor necrosis factor.

Streptococcus gordonii, a potential mucosal vaccine delivery vector, is proficient at colonizing murine oral mucosa; however, it often fails to elicit significant antibody titers against its vaccine antigen payloads. The poor response may be due to an inability of S. gordonii to elicit cytokines needed to suppress mucosal tolerance; exogenously supplied cytokines, such as TNF, could overcome this effect.

Immune response and alveolar bone resorption in a mouse model of Treponema denticola infection.

Treponema denticola is considered to be an agent strongly associated with periodontal disease. The lack of an animal infection model has hampered the understanding of T. denticola pathogenesis and the host's immune response to infection.

Expression of a functional single-chain variable-fragment antibody against complement receptor 1 in Streptococcus gordonii.

Streptococcus gordonii, an oral commensal organism, is a candidate vector for oral-vaccine development. Previous studies have shown that recombinant S. gordonii expressing heterologous antigens was weakly immunogenic when delivered intranasally.

Construction and characterization of single-chain variable fragment antibodies directed against the Bordetella pertussis surface adhesins filamentous hemagglutinin and pertactin.

A single-chain variable fragment (scFv) antibody library against Bordetella pertussis was constructed using M13 phage display. The library was enriched for phages surface displaying functional scFv by biopanning against B. pertussis immobilized on polystyrene plates.