PMID:20404080

Citation	Novak, EA, Shao, H, Daep, CA and Demuth, DR (2010) Autoinducer-2 and QseC control biofilm formation and in vivo virulence of Aggregatibacter actinomycetemcomitans. Infect. Immun. 78:2919-26
Abstract	Biofilm formation by the periodontal pathogen Aggregatibacter actinomycetemcomitans is dependent upon autoinducer-2 (AI-2)-mediated quorum sensing. However, the components that link the detection of the AI-2 signal to downstream gene expression have not been determined. One potential regulator is the QseBC two-component system, which is part of the AI-2-dependent response pathway that controls biofilm formation in Escherichia coli. Here we show that the expression of QseBC in A. actinomycetemcomitans is induced by AI-2 and that induction requires the AI-2 receptors, LsrB and/or RbsB. Additionally, inactivation of qseC resulted in reduced biofilm growth. Since the ability to grow in biofilms is essential for A. actinomycetemcomitans virulence, strains that were deficient in QseC or the AI-2 receptors were examined in an in vivo mouse model of periodontitis. The DeltaqseC mutant induced significantly less alveolar bone resorption than the wild-type strain (P < 0.02). Bone loss in animals infected with the DeltaqseC strain was similar to that in sham-infected animals. The DeltalsrB, DeltarbsB, and DeltalsrB DeltarbsB strains also induced significantly less alveolar bone resorption than the wild type (P < 0.03, P < 0.02, and P < 0.01, respectively). However, bone loss induced by a DeltaluxS strain was indistinguishable from that induced by the wild type, suggesting that AI-2 produced by indigenous microflora in the murine oral cavity may complement the DeltaluxS mutation. Together, these results suggest that the QseBC two-component system is part of the AI-2 regulon and may link the detection of AI-2 to the regulation of downstream cellular processes that are involved in biofilm formation and virulence of A. actinomycetemcomitans.
Links	PubMed PMC2897384 Online version:10.1128/IAI.01376-09
Keywords	Actinobacillus Infections/microbiology; Actinobacillus actinomycetemcomitans/genetics; Actinobacillus actinomycetemcomitans/pathogenicity; Actinobacillus actinomycetemcomitans/physiology; Animals; Biofilms/growth & development; Dental Plaque/microbiology; Disease Models, Animal; Gene Expression Regulation, Bacterial/physiology; Genes, Bacterial/genetics; Homoserine/analogs & derivatives; Homoserine/physiology; Lactones; Mice; Periodontitis/microbiology; Quorum Sensing/physiology; Reverse Transcriptase Polymerase Chain Reaction
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGGAC:D4EB47		GO:1900192: positive regulation of single-species biofilm formation	IMP: Inferred from Mutant Phenotype:	P	Figure 1 shows a large decrease in biofilm area and depth after the expression of QseC is repressed.	complete CACAO 4927

References

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