Post-translational modification by the Pgf glycosylation machinery modulates Streptococcus mutans OMZ175 physiology and virulence.

Streptococcus mutans is commonly associated with dental caries and the ability to form biofilms is essential for its pathogenicity. We recently identified the Pgf glycosylation machinery of S. mutans, responsible for the post-translational modification of the surface-associated adhesins Cnm and WapA.

Catalase produced by protects from HO stress-one more piece in the cross-kingdom synergism puzzle.

Co-infection with and is associated with dental caries, and their co-cultivation results in enhanced biofilm matrix production that contributes to increased virulence and caries risk. Moreover, the catalase-negative demonstrates increased oxidative stress tolerance when co-cultivated in biofilms with a catalase-producing yeast. Here, we sought to obtain mechanistic insights into the increased HO tolerance of when co-cultivated with clinical isolates of , and .

Involvement of the Streptococcus mutans PgfE and GalE 4-epimerases in protein glycosylation, carbon metabolism, and cell division.

Streptococcus mutans is a key pathogen associated with dental caries and is often implicated in infective endocarditis. This organism forms robust biofilms on tooth surfaces and can use collagen-binding proteins (CBPs) to efficiently colonize collagenous substrates, including dentin and heart valves. One of the best characterized CBPs of S.

Quantitative Analysis of Biofilm Removal Following Instrumentation with TRUShape and Vortex Blue File Systems: Microbiological Study.

Mesial roots and isthmuses of mandibular molars are difficult areas to obtain adequate disinfection of root canal walls, and consequently microorganisms can survive treatment. The present study compared, through real-time polymerase chain reaction (qPCR), the effectiveness of TRUShape (TS) (Dentsply Tulsa Dental Specialties, Tulsa, OK) and Vortex Blue (VB) (Dentsply Tulsa Dental Specialties, Tulsa, OK) in removing () from the mesial canals and isthmuses of mandibular molars. Fifty extracted human lower molars were inoculated with OG1RF for 14 days, and then an initial bacterial sample was collected with paper points from mesiobuccal and mesiolingual canals and isthmuses.

Amyloid Aggregates Are Localized to the Nonadherent Detached Fraction of Aging Streptococcus mutans Biofilms.

The number of bacterial species recognized to utilize purposeful amyloid aggregation within biofilms continues to grow. The oral pathogen Streptococcus mutans produces several amyloidogenic proteins, including adhesins P1 (also known as AgI/II, PAc) and WapA, whose truncation products, namely, AgII and AgA, respectively, represent the amyloidogenic moieties. Amyloids demonstrate common biophysical properties, including recognition by Thioflavin T (ThT) and Congo red (CR) dyes that bind to the cross β-sheet quaternary structure of amyloid aggregates.

ZccE is a Novel P-type ATPase That Protects Streptococcus mutans Against Zinc Intoxication.

Zinc is a trace metal that is essential to all forms of life, but that becomes toxic at high concentrations. Because it has both antimicrobial and anti-inflammatory properties and low toxicity to mammalian cells, zinc has been used as a therapeutic agent for centuries to treat a variety of infectious and non-infectious conditions. While the usefulness of zinc-based therapies in caries prevention is controversial, zinc is incorporated into toothpaste and mouthwash formulations to prevent gingivitis and halitosis.

c-di-AMP Is Essential for the Virulence of .

Second messenger nucleotides are produced by bacteria in response to environmental stimuli and play a major role in the regulation of processes associated with bacterial fitness, including but not limited to osmoregulation, envelope homeostasis, central metabolism, and biofilm formation. In this study, we uncovered the biological significance of c-di-AMP in the opportunistic pathogen Enterococcus faecalis by isolating and characterizing strains lacking genes responsible for c-di-AMP synthesis () and degradation ( and ). Using complementary approaches, we demonstrated that either complete loss of c-di-AMP (Δ strain) or c-di-AMP accumulation (Δ, Δ, and Δ Δ strains) drastically impaired general cell fitness and virulence of E.

Amyloid Aggregation of Streptococcus mutans Cnm Influences Its Collagen-Binding Activity.

The gene, coding for the glycosylated collagen- and laminin-binding surface adhesin Cnm, is found in the genomes of approximately 20% of Streptococcus mutans clinical isolates and is associated with systemic infections and increased caries risk. Other surface-associated collagen-binding proteins of S. mutans, such as P1 and WapA, have been demonstrated to form an amyloid quaternary structure with functional implications within biofilms.

Association of Candida albicans and Cbp Streptococcus mutans with early childhood caries recurrence.

Early childhood caries (ECC) recurrence occurs in approximately 40% of treated cases within one year. The association of Streptococcus mutans and Candida albicans with the onset of ECC is well known. Also, S.

Zinc import mediated by AdcABC is critical for colonization of the dental biofilm by Streptococcus mutans in an animal model.

Trace metals are essential to all domains of life but toxic when found at high concentrations. Although the importance of iron in host-pathogen interactions is firmly established, contemporary studies indicate that other trace metals, including manganese and zinc, are also critical to the infectious process. In this study, we sought to identify and characterize the zinc uptake system(s) of Streptococcus mutans, a keystone pathogen in dental caries and a causative agent of bacterial endocarditis.

Increased Oxidative Stress Tolerance of a Spontaneously Occurring Gene Mutation in Streptococcus mutans UA159.

The ability of bacteria, such as the dental pathogen , to coordinate a response against damage-inducing oxidants is a critical aspect of their pathogenicity. The oxidative stress regulator SpxA1 has been demonstrated to be a major player in the ability of to withstand both disulfide and peroxide stresses. While studying spontaneously occurring variants of an Δ strain, we serendipitously discovered that our UA159 host strain bore a single-nucleotide deletion within the coding region of , resulting in a premature truncation of the encoded protein.

Detection of Streptococcus mutans in symptomatic and asymptomatic infected root canals.

Objectives: To investigate the presence of Streptococcus mutans in root canals of symptomatic necrotic teeth (SNT) and their associated acute apical abscesses (AAA) and in the root canals of asymptomatic necrotic teeth (ANT). It also aimed to investigate the presence of the cnm and cbm genes in specimens that harbored S. mutans.

Functional Analysis of the Collagen Binding Proteins of Streptococcus parasanguinis FW213.

is a dominant isolate of dental plaque and an opportunistic pathogen associated with subacute endocarditis. As the expression of collagen binding proteins (CBPs) could promote the establishment of in the host, the functions of three putative CBP-encoding loci, Spaf_0420, Spaf_1570, and Spaf_1573, were analyzed using isogenic mutant strains. It was revealed that FW213 bound effectively to fibronectin and type I collagen, but the strain's affinity for laminin and type IV collagen was quite low.

is a target of the two-component systems VicRK and CovR required for systemic virulence of .

, a cariogenic species, is often associated with cardiovascular infections. Systemic virulence of specific serotypes has been associated with the expression of the collagen- and laminin-binding protein Cnm, which is transcriptionally regulated by VicRK and CovR. In this study, we characterized a VicRK- and CovR-regulated gene, , coding for a conserved endopeptidase.

Regulatory circuits controlling Spx levels in Streptococcus mutans.

Spx is a major regulator of stress responses in Firmicutes. In Streptococcus mutans, two Spx homologues, SpxA1 and SpxA2, were identified as mediators of oxidative stress responses but the regulatory circuits controlling their levels and activity are presently unknown. Comparison of SpxA1 and SpxA2 protein sequences revealed differences at the C-terminal end, with SpxA1 containing an unusual number of acidic residues.

Manganese Uptake, Mediated by SloABC and MntH, Is Essential for the Fitness of Streptococcus mutans.

Early epidemiological studies implicated manganese (Mn) as a possible caries-promoting agent, while laboratory studies have indicated that manganese stimulates the expression of virulence-related factors in the dental pathogen To better understand the importance of manganese homeostasis to pathophysiology, we first used RNA sequencing to obtain the global transcriptional profile of UA159 grown under Mn-restricted conditions. Among the most highly expressed genes were those of the entire operon, encoding a dual iron/manganese transporter, and an uncharacterized gene, here , that codes for a protein bearing strong similarity to Nramp-type transporters. While inactivation of , which encodes the lipoprotein receptor of the SloABC system, or of alone had no major consequence for the overall fitness of , simultaneous inactivation of and (Δ Δ) impaired growth and survival under Mn-restricted conditions, including in human saliva or in the presence of calprotectin.

The Biology of .

As a major etiological agent of human dental caries, resides primarily in biofilms that form on the tooth surfaces, also known as dental plaque. In addition to caries, is responsible for cases of infective endocarditis with a subset of strains being indirectly implicated with the onset of additional extraoral pathologies. During the past 4 decades, functional studies of have focused on understanding the molecular mechanisms the organism employs to form robust biofilms on tooth surfaces, to rapidly metabolize a wide variety of carbohydrates obtained from the host diet, and to survive numerous (and frequent) environmental challenges encountered in oral biofilms.

Biology of Oral Streptococci.

Bacteria belonging to the genus are the first inhabitants of the oral cavity, which can be acquired right after birth and thus play an important role in the assembly of the oral microbiota. In this article, we discuss the different oral environments inhabited by streptococci and the species that occupy each niche. Special attention is given to the taxonomy of , because this genus is now divided into eight distinct groups, and oral species are found in six of them.

CovR and VicRKX Regulate Transcription of the Collagen Binding Protein Cnm of Streptococcus mutans.

Cnm is a surface-associated protein present in a subset of strains that mediates binding to extracellular matrices, intracellular invasion, and virulence. Here, we showed that transcription is controlled by the global regulators CovR and VicRKX. analysis identified multiple putative CovR- and VicR-binding motifs in the regulatory region of as well as in the downstream gene , which is associated with the posttranslational modification of Cnm.

Disruption of a Novel Iron Transport System Reverses Oxidative Stress Phenotypes of a Mutant Strain of Streptococcus mutans.

The Dps-like peroxide resistance protein (Dpr) is essential for HO stress tolerance and aerobic growth of the oral pathogen Dpr accumulates during oxidative stress, protecting the cell by sequestering iron ions and thereby preventing the generation of toxic hydroxyl radicals that result from the interaction of iron with HO Previously, we reported that the SpxA1 and SpxA2 regulators positively regulate expression of in Using an antibody raised against Dpr, we confirmed at the protein level the central and cooperative nature of SpxA1 and SpxA2 regulation in Dpr production. During phenotypic characterization of the Δ strain, we observed the appearance of distinct colony variants, which sometimes lost the oxidative stress sensitivity typical of Δ strains. Whole-genome sequencing of these phenotypically distinct Δ isolates revealed that a putative iron transporter operon, , was a genomic hot spot with multiple single nucleotide polymorphisms identified within the different isolates.

Characterization of the pgf operon involved in the posttranslational modification of Streptococcus mutans surface proteins.

Protein glycosylation has been described as the most abundant and complex post-translational modification occurring in nature. Recent studies have enhanced our view of how this modification occurs in bacteria highlighting the role of protein glycosylation in various processes such as biofilm formation, virulence and host-microbe interactions. We recently showed that the collagen- and laminin-binding adhesin Cnm of the dental pathogen Streptococcus mutans is post-translationally modified by the PgfS glycosyltransferase.

Whole genome sequence and phenotypic characterization of a Cbm serotype e strain of Streptococcus mutans.

We report the whole genome sequence of the serotype e Cbm strain LAR01 of Streptococcus mutans, a dental pathogen frequently associated with extra-oral infections. The LAR01 genome is a single circular chromosome of 2.1 Mb with a GC content of 36.

Transcriptome responses of Streptococcus mutans to peroxide stress: identification of novel antioxidant pathways regulated by Spx.

The oxidative stress regulator Spx is ubiquitously found among Gram-positive bacteria. Previously, we reported identification of two Spx proteins in Streptococcus mutans - SpxA1 was the primary activator of oxidative stress genes whereas SpxA2 served a backup role. Here, we used RNA sequencing to uncover the scope of the HO (peroxide)-stress regulon and to further explore the significance of Spx regulation in S.

Pro-inflammatory Analysis of Macrophages in Contact with Titanium Particles and Porphyromonas gingivalis.

During insertion of titanium dental implants, particles may shear from the implant to the periimplant region causing osteolysis, and their association with bacteria can exacerbate the inflammatory reaction. However, the association of a high invasive bacterium from the oral cavity, Porphyromonas gingivalis (Pg), and titanium particles remains unknown. This study evaluated pro-inflammatory reaction of human macrophages in contact with micro and nanoparticles of titanium associated with Porphyromonas gingivalis lipopolysaccharide (PgLPS).