Complete Genome Sequence of the Serotype k Streptococcus mutans Strain LJ23

Aikawa, Chihiro; Furukawa, Nayuta; Watanabe, Takayasu; Minegishi, Kana; Furukawa, Asuka; Eishi, Yoshinobu; Oshima, Koichiro; Kurokawa, Ken; Hattori, Masahira; Nakano, Kazuhiko; Maruyama, Fumito; Nakagawa, Ichirô; Ooshima, Takashi

doi:10.1128/jb.00350-12

Cited by 19 publications

(18 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The function of this TCS in S. mutans has yet to be determined. However, a recently sequenced serotype k strain (LJ23) also contains TCS-15 [73]. In our analysis of the genomes of the 57 isolates from across the globe, TCS-15 was found in 16 of the 57 strains, and was distributed across all serotypes.…”

Section: Resultsmentioning

confidence: 83%

Phenotypic Heterogeneity of Genomically-Diverse Isolates of Streptococcus mutans

et al. 2013

View full text Add to dashboard Cite

High coverage, whole genome shotgun (WGS) sequencing of 57 geographically- and genetically-diverse isolates of Streptococcus mutans from individuals of known dental caries status was recently completed. Of the 57 sequenced strains, fifteen isolates, were selected based primarily on differences in gene content and phenotypic characteristics known to affect virulence and compared with the reference strain UA159. A high degree of variability in these properties was observed between strains, with a broad spectrum of sensitivities to low pH, oxidative stress (air and paraquat) and exposure to competence stimulating peptide (CSP). Significant differences in autolytic behavior and in biofilm development in glucose or sucrose were also observed. Natural genetic competence varied among isolates, and this was correlated to the presence or absence of competence genes, comCDE and comX, and to bacteriocins. In general strains that lacked the ability to become competent possessed fewer genes for bacteriocins and immunity proteins or contained polymorphic variants of these genes. WGS sequence analysis of the pan-genome revealed, for the first time, components of a Type VII secretion system in several S. mutans strains, as well as two putative ORFs that encode possible collagen binding proteins located upstream of the cnm gene, which is associated with host cell invasiveness. The virulence of these particular strains was assessed in a wax-worm model. This is the first study to combine a comprehensive analysis of key virulence-related phenotypes with extensive genomic analysis of a pathogen that evolved closely with humans. Our analysis highlights the phenotypic diversity of S. mutans isolates and indicates that the species has evolved a variety of adaptive strategies to persist in the human oral cavity and, when conditions are favorable, to initiate disease.

show abstract

Section: Resultsmentioning

confidence: 83%

Phenotypic Heterogeneity of Genomically-Diverse Isolates of Streptococcus mutans

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The sequence alignment reveals that the MecA protein in S. mutans is highly homologous to those in Streptococcus agalactiae A909 (67% identity), Streptococcus pyogenes M1 GAS (63% identity), and S. thermophilus LMD-9 (57% identity). The MecA proteins are well conserved among S. mutans strains, since all four fully sequenced S. mutans strains, strains UA159, GS-5, NN2025, and LJ23, contain a putative MecA in their genomes (30,(33)(34)(35). In particular, the MecA proteins in S. mutans strains share high levels of conservation at the N-terminal domain (NTD) and C-terminal domain (CTD) with those of S. thermophilus and B. subtilis (24)(25)(26)(27)(28), suggesting that MecA in S. mutans might act as an adaptor protein to interact with its partners to regulate competence and stress response in a manner similar to the proteins in S. thermophilus and B. subtilis (24)(25)(26)(27)(28).…”

Section: Resultsmentioning

confidence: 99%

“…Recently, a similar regulatory mechanism involving sequestration of SigX by a SigX-MecA-ClpC complex has been reported in Streptococcus thermophilus, in which the type I ComRS system primarily regulates the expression of comX for genetic competence (28,29). The S. mutans genome lacks both comW and comK, but it contains all of the genes encoding SigX, MecA, ClpC, and ClpP (30)(31)(32)(33)(34)(35). Whether MecA in S. mutans plays a functional role in the regulation of the SigX activity and competence was unknown.…”

mentioning

confidence: 99%

MecA Protein Acts as a Negative Regulator of Genetic Competence in Streptococcus mutans

et al. 2013

View full text Add to dashboard Cite

c Streptococcus mutans develops competence for genetic transformation through a complex network that receives inputs from at least two signaling peptides, competence-stimulating peptide (CSP) and sigX-inducing peptide (XIP). The key step of competence induction is the transcriptional activation of comX, which encodes an alternative sigma factor, SigX ( X ), controlling the expression of late competence genes essential for DNA uptake and recombination. In this study, we provide evidence that MecA acts as a negative regulator in the posttranslational regulation of SigX in S. mutans. Using luxAB transcriptional reporter strains, we demonstrate that MecA represses the expression of late competence genes in S. mutans grown in a complex medium that is subpermissive for competence induction by CSP. The negative regulation of competence by MecA requires the presence of a functional SigX. Accordingly, inactivation of MecA results in a prolonged competence state of S. mutans under this condition. We have also found that the AAA؉ protease ClpC displays a similar repressing effect on late competence genes, suggesting that both MecA and ClpC function coordinately to regulate competence in the same regulatory circuit in S. mutans. This suggestion is strongly supported by the results of bacterial two-hybrid assays, which demonstrate that MecA interacts with both SigX and ClpC, forming a ternary SigX-MecA-ClpC complex. Western blot analysis also confirms that inactivation of MecA or ClpC results in the intracellular accumulation of the SigX in S. mutans. Together, our data support the notion that MecA mediates the formation of a ternary SigX-MecA-ClpC complex that sequesters SigX and thereby negatively regulates genetic competence in S. mutans.

show abstract

“…Analysis of the complete sequence from UA159 showed that the six genes encoding LPXTG-anchored proteins are pac, fruA, dexA, gbpC, wapA, and wapE (10), all of which have also been identified in strains NN2025, LJ23, and GS-5 (11)(12)(13). The approximately 190-kDa protein antigen (PA) encoded by pac, which is also known as SpaP, P1, and other designations, is expressed in extremely small amounts in serotype k strains compared with the levels found in strains commonly present in the oral cavity.…”

Section: Nfective Endocarditis (Ie) Is a Life-threatening Disease Fmentioning

confidence: 99%

Contribution of the Interaction of Streptococcus mutans Serotype k Strains with Fibrinogen to the Pathogenicity of Infective Endocarditis

et al. 2014

View full text Add to dashboard Cite

dStreptococcus mutans, a pathogen responsible for dental caries, is occasionally isolated from the blood of patients with bacteremia and infective endocarditis (IE). Our previous study demonstrated that serotype k-specific bacterial DNA is frequently detected in S. mutans-positive heart valve specimens extirpated from IE patients. However, the reason for this frequent detection remains unknown. In the present study, we analyzed the virulence of IE from S. mutans strains, focusing on the characterization of serotype k strains, most of which are positive for the 120-kDa cell surface collagen-binding protein Cbm and negative for the 190-kDa protein antigen (PA) known as SpaP, P1, antigen I/II, and other designations. Fibrinogen-binding assays were performed with 85 clinical strains classified by Cbm and PA expression levels. The Cbm ؉ /PA ؊ group strains had significantly higher fibrinogen-binding rates than the other groups. Analysis of platelet aggregation revealed that SA31, a Cbm ؉ /PA ؊ strain, induced an increased level of aggregation in the presence of fibrinogen, while negligible aggregation was induced by the Cbmdefective isogenic mutant SA31CBD. A rat IE model with an artificial impairment of the aortic valve created using a catheter showed that extirpated heart valves in the SA31 group displayed a prominent vegetation mass not seen in those in the SA31CBD group. These findings could explain why Cbm ؉ /PA ؊ strains are highly virulent and are related to the development of IE, and the findings could also explain the frequent detection of serotype k DNA in S. mutans-positive heart valve clinical specimens.

show abstract

Complete Genome Sequence of the Serotype k Streptococcus mutans Strain LJ23

Abstract: e Streptococcus mutans is the major pathogen of dental caries and occasionally causes infective endocarditis. Here we report the complete genome sequence of serotype k S. mutans strain LJ23, which was recently isolated from the oral cavity of a Japanese patient.

Cited by 19 publications

References 17 publications

Phenotypic Heterogeneity of Genomically-Diverse Isolates of Streptococcus mutans

Phenotypic Heterogeneity of Genomically-Diverse Isolates of Streptococcus mutans

MecA Protein Acts as a Negative Regulator of Genetic Competence in Streptococcus mutans

Contribution of the Interaction of Streptococcus mutans Serotype k Strains with Fibrinogen to the Pathogenicity of Infective Endocarditis

Contact Info

Product

Resources

About