Diversity of β‐hemolysins produced by the human opportunistic streptococci

Tabata, Atsushi; Nagamune, Hideaki

doi:10.1111/1348-0421.12936

Cited by 11 publications

(11 citation statements)

References 135 publications

(172 reference statements)

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“…Oral mitis group streptococci are close relatives of pathogenic S. pneumoniae; however, they do not produce some pneumococcal virulence factors, such as cytotoxin (pneumolysin). 5,21 Thus, some pneumococcal virulence factors might not be necessary to infect or colonize in the oral cavity. By contrast, almost all oral streptococci produce GTFs, suggesting that GTFs and their glucan products provide an advantage in inhabiting the oral cavity.…”

Section: Discussionmentioning

confidence: 99%

“…4,[7][8][9][10] The number of members in the mitis group is increasing, and at present, more than 20 species have been reported. 5,[10][11][12][13] As the characteristics of the newly reported species have not been established yet, [11][12][13] this review will mainly summarize studies on three species, namely, S. oralis, S. sanguinis, and S. gordonii.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the 16S ribosomal RNA gene sequences, streptococci can be organized into six major groups (Figure 1). 3–5 The well‐known species of the mitis group are Streptococcus mitis and Streptococcus pneumoniae (pneumococcus). Several species of this group are major oral inhabitants, including Streptococcus oralis, Streptococcus sanguinis , and Streptococcus gordonii 4,6–9 …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Oral mitis group streptococci: A silent majority in our oral cavity

Okahashi

Nakata

Kuwata

et al. 2022

Microbiology and Immunology

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Members of the oral mitis group streptococci including Streptococcus oralis, Streptococcus sanguinis, and Streptococcus gordonii are the most abundant inhabitants of human oral cavity and dental plaque, and have been implicated in infectious complications such as bacteremia and infective endocarditis. Oral mitis group streptococci are genetically close to Streptococcus pneumoniae; however, they do not produce cytolysin (pneumolysin), which is a key virulence factor of S. pneumoniae. Similar to S. pneumoniae, oral mitis group streptococci possess several cell surface proteins that bind to the cell surface components of host mammalian cells. S. sanguinis expresses long filamentous pili that bind to the matrix proteins of host cells. The cell wall–anchored nuclease of S. sanguinis contributes to the evasion of the neutrophil extracellular trap by digesting its web‐like extracellular DNA. Oral mitis group streptococci produce glucosyltransferases, which synthesize glucan (glucose polymer) from sucrose of dietary origin. Neuraminidase (NA) is a virulent factor in oral mitis group streptococci. Influenza type A virus (IAV) relies on viral NA activity to release progeny viruses from infected cells and spread the infection, and NA‐producing oral streptococci elevate the risk of IAV infection. Moreover, oral mitis group streptococci produce hydrogen peroxide (H2O2) as a by‐product of sugar metabolism. Although the concentrations of streptococcal H2O2 are low (1–2 mM), they play important roles in bacterial competition in the oral cavity and evasion of phagocytosis by host macrophages and neutrophils. In this review, we intended to describe the diverse pathogenicity of oral mitis group streptococci.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oral mitis group streptococci: A silent majority in our oral cavity

Okahashi

Nakata

Kuwata

et al. 2022

Microbiology and Immunology

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“…ILY is important for the pathogenicity of S. intermedius in humans [ 36 ]. In addition, investigations on the pathogenicity of other opportunistic streptococci that inhabit the oral cavity of humans revealed that a group of S. mitis strains displayed obvious β-hemolysis on blood agar [ 37 ]. The first reported β-hemolytic factor produced by S. mitis , mitilysin (MLY), is a typical CDC composed of four domains with extensive homology to pneumolysin (PLY) [ 38 ].…”

Section: Introductionmentioning

confidence: 99%

Dual functions of discoidinolysin, a cholesterol-dependent cytolysin with N-terminal discoidin domain produced from Streptococcus mitis strain Nm-76

Tabata

Matsumoto

Fujimoto

et al. 2022

Journal of Oral Microbiology

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Background Some strains of Streptococcus mitis exhibit β-hemolysis due to the β-hemolytic activity of cholesterol-dependent cytolysin (CDC). Recently, a gene encoding an atypical lectinolysin-related CDC was found in S. mitis strain Nm-76. However, the product of this gene remains uncharacterized. We aimed to characterize this atypical CDC and its molecular functions and contribution to the pathogenicity of S. mitis strain Nm-76. Methods Phylogenetic analysis of the CDC gene was conducted based on the web-deposited information. The molecular characteristics of CDC were investigated using a gene-deletion mutant strain and recombinant proteins expressed in Escherichia coli . Results The gene encoding CDC found in Nm-76 and its homolog are distributed among many S. mitis strains. This CDC is phylogenetically different from other previously characterized CDCs, such as S. mitis -derived human platelet aggregation factor (Sm-hPAF)/lectinolysin and mitilysin. Because this CDC possesses an additional N-terminal domain, including a discoidin motif, it was termed discoidinolysin (DLY). In addition to the preferential lysis of human cells, DLY displayed N-terminal domain-dependent facilitation of human erythrocyte aggregation and intercellular associations between human cells. Conclusion DLY functions as a hemolysin/cytolysin and erythrocyte aggregation/intercellular association molecule. This dual-function DLY could be an additional virulence factor in S. mitis .

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“…Pneumolysin (PLY), a cholesterol-dependent cytolysin, is a virulence factor of S. pneumoniae that is released from cells via autolysis [ 4 , 5 ]. PLY is found in virtually all pneumococcal isolates and plays a key role in bacterial colonization, invasion, and inflammation [ 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

Matcha Green Tea Exhibits Bactericidal Activity against Streptococcus pneumoniae and Inhibits Functional Pneumolysin

et al. 2021

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Streptococcus pneumoniae is a causative pathogen of several human infectious diseases including community-acquired pneumonia. Pneumolysin (PLY), a pore-forming toxin, plays an important role in the pathogenesis of pneumococcal pneumonia. In recent years, the use of traditional natural substances for prevention has drawn attention because of the increasing antibacterial drug resistance of S. pneumoniae. According to some studies, green tea exhibits antibacterial and antitoxin activities. The polyphenols, namely the catechins epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC) are largely responsible for these activities. Although matcha green tea provides more polyphenols than green tea infusions, its relationship with pneumococcal pneumonia remains unclear. In this study, we found that treatment with 20 mg/mL matcha supernatant exhibited significant antibacterial activity against S. pneumoniae regardless of antimicrobial resistance. In addition, the matcha supernatant suppressed PLY-mediated hemolysis and cytolysis by inhibiting PLY oligomerization. Moreover, the matcha supernatant and catechins inhibited PLY-mediated neutrophil death and the release of neutrophil elastase. These findings suggest that matcha green tea reduces the virulence of S. pneumoniae in vitro and may be a promising agent for the treatment of pneumococcal infections.

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Diversity of β‐hemolysins produced by the human opportunistic streptococci

Cited by 11 publications

References 135 publications

Oral mitis group streptococci: A silent majority in our oral cavity

Oral mitis group streptococci: A silent majority in our oral cavity

Dual functions of discoidinolysin, a cholesterol-dependent cytolysin with N-terminal discoidin domain produced from Streptococcus mitis strain Nm-76

Matcha Green Tea Exhibits Bactericidal Activity against Streptococcus pneumoniae and Inhibits Functional Pneumolysin

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