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Invasion of Human Cells by a Bacterial Pathogen
07:15

Invasion of Human Cells by a Bacterial Pathogen

Published on: March 21, 2011

Two epithelial cell invasion-related loci of the oral pathogen Actinobacillus actinomycetemcomitans

L Li1, D Matevski, M Aspiras

  • 1University of Toronto, Faculty of Dentistry, Toronto, Ontario, Canada.

Oral Microbiology and Immunology
|December 18, 2003
PubMed

Insights

Two invasion-related genes, apiA and apiBC, from Actinobacillus actinomycetemcomitans were identified. These genes influence bacterial invasion and adhesion, with ApiA enhancing binding to collagen and fibronectin, and ApiB affecting invasion.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogenesis

Background:

  • Actinobacillus actinomycetemcomitans is an oral pathogen.
  • Understanding its invasion mechanisms is crucial for developing therapeutic strategies.

Purpose of the Study:

  • To identify and characterize invasion-related genes in Actinobacillus actinomycetemcomitans.
  • To investigate the role of these genes in bacterial adhesion and invasion.

Main Methods:

  • Isolation and cloning of invasion-related loci (apiA, apiBC) from A. actinomycetemcomitans UT32 into Escherichia coli.
  • Characterization of protein expression and phenotypes in E. coli transformants.
  • Construction and analysis of apiA and apiB deficient mutants in A. actinomycetemcomitans.
  • Adhesion assays using collagen and fibronectin.
  • Cell invasion assays using KB cells.

Main Results:

  • The apiA gene encodes a 32.5 kDa protein (ApiA) that, when expressed in E. coli, alters colony morphology and mediates binding to collagen types II, III, V, and fibronectin.
  • The apiBC operon encodes ApiB (130.1 kDa) and ApiC (70.6 kDa) proteins, conferring enhanced binding to collagen type III in E. coli.
  • ApiB-deficient mutants showed a 4-fold decrease in KB cell invasion, while ApiA-deficient mutants exhibited increased invasion.
  • Both loci are conserved in A. actinomycetemcomitans strains, with polymorphism observed in apiBC.
  • Deduced protein sequences are homologous to the YadA adhesin/invasin family.

Conclusions:

  • ApiA and ApiBC are novel invasion-related loci in Actinobacillus actinomycetemcomitans.
  • ApiA functions as an adhesin, mediating binding to host extracellular matrix components.
  • ApiB plays a significant role in bacterial invasion of host cells.
  • These findings contribute to understanding the molecular mechanisms of A. actinomycetemcomitans pathogenesis.

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