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PMID:12654815

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Citation

Merritt, J, Qi, F, Goodman, SD, Anderson, MH and Shi, W (2003) Mutation of luxS affects biofilm formation in Streptococcus mutans. Infect. Immun. 71:1972-9

Abstract

Quorum sensing is a bacterial mechanism for regulating gene expression in response to changes in population density. Many bacteria are capable of acyl-homoserine lactone-based or peptide-based intraspecies quorum sensing and luxS-dependent interspecies quorum sensing. While there is good evidence about the involvement of intraspecies quorum sensing in bacterial biofilm, little is known about the role of luxS in biofilm formation. In this study, we report for the first time that luxS-dependent quorum sensing is involved in biofilm formation of Streptococcus mutans. S. mutans is a major cariogenic bacterium in the multispecies bacterial biofilm commonly known as dental plaque. An ortholog of luxS for S. mutans was identified using the data available in the S. mutans genome project (http://www.genome.ou.edu/smutans.html). Using an assay developed for the detection of the LuxS-associated quorum sensing signal autoinducer 2 (AI-2), it was demonstrated that this ortholog was able to complement the luxS negative phenotype of Escherichia coli DH5alpha. It was also shown that AI-2 is indeed produced by S. mutans. AI-2 production is maximal during mid- to late-log growth in batch culture. Mutant strains devoid of the luxS gene were constructed and found to be defective in producing the AI-2 signal. There are also marked phenotypic differences between the wild type and the luxS mutants. Microscopic analysis of in vitro-grown biofilm structure revealed that the luxS mutant biofilms adopted a much more granular appearance, rather than the relatively smooth, confluent layer normally seen in the wild type. These results suggest that LuxS-dependent signal may play an important role in biofilm formation of S. mutans.

Links

PubMed PMC152054

Keywords

Amino Acid Sequence; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biofilms/growth & development; Carbon-Sulfur Lyases; Culture Media; Escherichia coli/genetics; Escherichia coli/metabolism; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Homoserine/analogs & derivatives; Homoserine/metabolism; Humans; Lactones/metabolism; Molecular Sequence Data; Mutation; Sequence Alignment; Signal Transduction; Streptococcus mutans/genetics; Streptococcus mutans/growth & development

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

STRMU:LUXS

GO:0009369: quorum sensing signal generator activity

ECO:0000316:

UniProtKB:P45578


1

Figure 2: A plasmid containing the luxS gene from S. mutans complements the mutation in AI-2 producing deficient E. coli strain DH5alpha, showing that the LuxS protein in S. mutans produces AI-2

complete

STRMU:LUXS

GO:0044011: single-species biofilm formation on inanimate substrate

ECO:0000315:

P

Figure 5: luxS mutants of S. mutans form altered biofilms, that are more suceptible to SDS

complete


See also

References

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