The pga gene cluster in Aggregatibacter actinomycetemcomitans is necessary for the development of natural competence in Ca2+-promoted biofilms

K. Hisano, O. Fujise, M. Miura, T. Hamachi, E. Matsuzaki, F. Nishimura

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Natural competence is the ability of bacteria to incorporate extracellular DNA into their genomes. This competence is affected by a number of factors, including Ca2+ utilization and biofilm formation. As bacteria can form thick biofilms in the presence of extracellular Ca2+, the additive effects of Ca2+-promoted biofilm formation on natural competence should be examined. We evaluated natural competence in Aggregatibacter actinomycetemcomitans, an important periodontal pathogen, in the context of Ca2+-promoted biofilms, and examined whether the pga gene cluster, required for bacterial cell aggregation, is necessary for competence development. The A. actinomycetemcomitans cells grown in the presence of 1 mm CaCl2 exhibited enhanced cell aggregation and increased levels of cell-associated Ca2+. Biofilm-derived cells grown in the presence of Ca2+ exhibited the highest levels of natural transformation frequency and enhanced expression of the competence regulator gene, tfoX. Natural competence was enhanced by the additive effects of Ca2+-promoted biofilms, in which high levels of pga gene expression were also detected. Mutation of the pga gene cluster disrupted biofilm formation and competence development, suggesting that these genes play a critical role in the ability of A. actinomycetemcomitans to adapt to its natural environment. The Ca2+-promoted biofilms may enhance the ability of bacteria to acquire extracellular DNA.

Original languageEnglish
Pages (from-to)79-89
Number of pages11
JournalMolecular Oral Microbiology
Volume29
Issue number2
DOIs
Publication statusPublished - Apr 2014

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Immunology
  • Dentistry(all)
  • Microbiology (medical)

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