Characterization of the conformational epitope of Guy's 13, a monoclonal antibody that prevents Streptococcus mutans colonization in humans.
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ABSTRACT:
SUBMITTER: van Dolleweerd CJ
PROVIDER: S-EPMC145350 | biostudies-literature | 2003 Feb
REPOSITORIES: biostudies-literature
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Characterization of the conformational epitope of Guy's 13, a monoclonal antibody that prevents Streptococcus mutans colonization in humans.
van Dolleweerd Craig J CJ Chargelegue Daniel D Ma Julian K-C JK
Infection and immunity 20030201 2
Guy's 13 is a mouse monoclonal antibody which recognizes streptococcal antigen I/II (SA I/II), a major cell surface glycoprotein of Streptococcus mutans. In a number of clinical trials, this antibody has been shown to prevent colonization in the human oral cavity. The aim of this study was to identify the SA I/II epitope recognized by Guy's 13. The data suggest that the epitope is conformational, delimited by two noncontiguous regions of the antigen: residues 45 to 457, within the N-terminal hal ...[more]
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Project description:Plasmalogen is a specific glycerophospholipid present in both animal and bacterial organisms. It plays a crucial function in eukaryotic cellular processes and is closely related to several human diseases, including neurological disorders and cancers. Nonetheless, the precise biological role of plasmalogen in bacteria is not well understood. In this study, we identified SMU_438c as the enzyme responsible for plasmalogen production in Streptococcus mutans under anaerobic conditions. The heterologous expression of SMU_438c in a plasmalogen-negative strain, Streptococcus sanguinis, resulted in the production of plasmalogen, indicating that this enzyme is sufficient for plasmalogen production. Additionally, the plasmalogen-deficient S. mutans exhibited significantly lower acid tolerance and diminished its colonization in Drosophila flies compared to the wild-type strain and complemented strain. In summary, our data suggest that plasmalogen plays a vital role in bacterial stress tolerance and in vivo colonization.ImportanceThis study sheds light on the biological role of plasmalogen, a specific glycerophospholipid, in bacteria, particularly in Streptococcus mutans. Plasmalogens are known for their significant roles in eukaryotic cells and have been linked to human diseases like neurological disorders and cancers. The enzyme SMU_438c, identified as essential for plasmalogen production under anaerobic conditions, was crucial for acid tolerance and in vivo colonization in Drosophila by S. mutans, underscoring its importance in bacterial stress response and colonization. These findings bridge the knowledge gap in bacterial physiology, highlighting plasmalogen's role in microbial survival and offering potential insights into microbial pathogenesis and host-microbe interactions.
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Project description:Streptococcus mutans is a common constituent of dental plaque and a major etiologic agent of dental caries (tooth decay). In this study, we elucidated the biosynthetic pathway encoded by muc, a hybrid polyketide synthase and nonribosomal peptide synthetase (PKS/NRPS) biosynthetic gene cluster (BGC), present in a number of globally distributed S. mutans strains. The natural products synthesized by muc included three N-acyl tetramic acid compounds (reutericyclin and two novel analogues) and an unacylated tetramic acid (mutanocyclin). Furthermore, the enzyme encoded by mucF was identified as a novel class of membrane-associated aminoacylases and was responsible for the deacylation of reutericyclin to mutanocyclin. A large number of hypothetical proteins across a broad diversity of bacteria were homologous to MucF, suggesting that this may represent a large family of unexplored acylases. Finally, S. mutans utilized the reutericyclin produced by muc to impair the growth of neighboring oral commensal bacteria. Since S. mutans must be able to out-compete these health-associated organisms to persist in the oral microbiota and cause disease, the competitive advantage conferred by muc suggests that this BGC is likely to be involved in S. mutans ecology and therefore dental plaque dysbiosis and the resulting caries pathogenesis.
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Project description:BackgroundStreptococcus mutans is a common cariogenic bacterium in the oral cavity involved in plaque formation. Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) has been introduced into tooth mousse to encourage remineralization of dental enamel. The aim of this research was to study the effect of tooth mousse containing CPP-ACP (GC Tooth Mousse®) or CPP-ACP with 0.2% fluoride (CPP-ACPF; GC Tooth Mousse Plus®; GCP) on S. mutans planktonic growth and biofilm formation.MethodsS. mutans was cultivated in the presence of different dilutions of the tooth mousse containing CPP-ACP or CPP-ACPF, and the planktonic growth was determined by ATP viability assay and counting colony-forming units (CFUs). The resulting biofilms were examined by crystal violet staining, MTT metabolic assay, confocal laser scanning microscopy (CLSM), and scanning electron microscope (SEM).ResultsThe CPP-ACP tooth mousse (GC) at a dilution of 5-50 mg/ml (0.5-5%) did not inhibit planktonic growth, and even increased the ATP content and the number of viable bacteria after a 24 h incubation. The same was observed for the CPP-ACPF tooth mousse (GCP), except for the higher concentrations (25 and 50 mg/ml) that led to a drop in the bacterial count. Importantly, both compounds significantly decreased S. mutans biofilm formation at dilutions as low as 1.5-3 mg/ml. 12.5 mg/ml GC and 6.25 mg/ml GCP inhibited biofilm formation by 90% after 4 h. After 24 h, the MBIC90 was 6.25 mg/ml for both. CLSM images confirmed the strong inhibitory effect GC and GCP had on biofilm formation when using 5 mg/ml tooth mousse. SEM images of those bacteria that managed to form biofilm in the presence of 5 mg/ml tooth mousse, showed alterations in the bacterial morphology, where the streptococci appear 25-30% shorter on the average than the control bacteria.ConclusionOur data show that the tooth mousse containing CPP-ACP reduces biofilm formation of the cariogenic bacterium S. mutans without killing the bacteria. The use of natural substances which inhibit biofilm development without killing the bacteria, has therapeutic benefits, especially in orthodontic pediatric patients.
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