Outer membrane protein 100, a versatile virulence factor of Actinobacillus actinomycetemcomitans

Mol Microbiol. 2003 Nov;50(4):1125-39. doi: 10.1046/j.1365-2958.2003.03748.x.


Actinobacillus actinomycetemcomitans (Aa) is one of the pathogenic bacteria involved in periodontal diseases. We have previously identified six major outer membrane proteins (Omps) of Aa Y4. Among them is an Omp with high molecular mass, designated Omp100, which has homology to a variety of virulence factors. Electron microscopic observation indicated that Omp100 is randomly localized on the cell surface of Aa. Aa Y4 has been shown to adhere and invade KB or normal human gingival keratinocytes. Anti-Omp100 antibody inhibited 50% of adhesion and 70% of invasion of Aa Y4 to KB cells. An Omp100 knock-out mutant had a decreased adhesion and invasion efficiency of 60%, compared with that of the wild type. Escherichia coli HB101 expressing Omp100 adhered twofold and invaded 10-fold more than the wild-type E. coli HB101. HB101 expressing Omp100 showed resistance to serum by trapping factor H, an inhibitor for C3b, with Omp100. Omp100 induced inflammatory cytokine responses of interleukin (IL)-8, IL-6 and tumour necrosis factor (TNF)alpha in epithelial cells, and induced IL-1beta and TNFalpha production in mouse macrophages. These results indicate that Omp100 is a versatile virulence factor that may demonstrate potential significance in the onset of periodontal diseases related to Aa.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Actinobacillus Infections / microbiology
  • Aggregatibacter actinomycetemcomitans / metabolism
  • Aggregatibacter actinomycetemcomitans / pathogenicity*
  • Aggregatibacter actinomycetemcomitans / ultrastructure
  • Animals
  • Bacterial Adhesion / physiology
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism*
  • Cells, Cultured
  • Complement Factor H / metabolism
  • Cytokines / genetics
  • Cytokines / metabolism
  • Escherichia coli / metabolism
  • Escherichia coli / ultrastructure
  • Female
  • Humans
  • Macrophages / immunology
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Mutation
  • Periodontal Diseases / microbiology
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Virulence Factors / genetics
  • Virulence Factors / metabolism*


  • Bacterial Outer Membrane Proteins
  • Cytokines
  • Recombinant Proteins
  • Virulence Factors
  • complement factor H, human
  • Complement Factor H