Fimbriae-associated genes are biofilm-forming factors in Aggregatibacter actinomycetemcomitans strains.
Aggregatibactor actinomycetemcomitans colonizes human periodontal lesions and is implicated in both aggressive periodontitis and chronic periodontitis. Clinical isolated colonies of A. actinomycetemcomitans were rough type. The rough type has a remarkable ability to adhere tenaciously to solid surfaces and colonize firmly. Rough type colonies change into smooth type colonies during the course of repeated inoculation and biofilm-forming activity ceases. Adherence by A. actinomycetemcomitans is mediated by the tight-adherence (tad) gene locus, which includes flp, rcpA and rcpB. In this study, we investigated the relationship between its biofilm-forming ability and expression of the flp, rcpA and rcpB genes associated with fimbriae protein production. First, we changed rough type strain organized biofilm on glass into smooth type and confirmed it by observation of biofilm on glass surfaces. Then, we carried out Real-Time PCR and found that expression of the rcpA and rcpB genes was clearly reduced in smooth type colonies. This suggests that expression of rcpA and rcpB plays a key role in biofilm formation by A. actinomycetemcomitans strains and the establishment of persistent infections in periodontal lesions.
Saito
Takayuki
T
Department of Removable Prosthodontics and Gerodontology, Tokyo Dental College, Chiba, Japan. saitot@tdc.ac.jp
Ishihara
Kazuyuki
K
Ryu
Masahiro
M
Okuda
Katsuji
K
Sakurai
Kaoru
K
D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics*; D001422:Bacterial Adhesion / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D055113:Chronic Periodontitis / Q000382:microbiology*; D003773:Dental Plaque / Q000382:microbiology; D010861:Fimbriae, Bacterial / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D018613:Microscopy, Confocal
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C113731:Flp protein, bacteria; C119576:RcpA protein, Actinobacillus actinomycetemcomitans; C119577:rcpB protein, Actinobacillus actinomycetemcomitans