The pga gene cluster in Aggregatibacter actinomycetemcomitans is necessary for the development of natural competence in Ca2+‐promoted biofilms. (7th February 2014)

• Record Type: Journal Article
• Authors: Hisano, K.; Fujise, O.; Miura, M.; Hamachi, T.; Matsuzaki, E.; Nishimura, F.
• Is Part Of: Molecular oral microbiology. Volume 29:Number 2(2014)
• Page Start: 79
• Page End: 89
• Publication Date: 2014-02-07
• Subjects: Mouth -- Microbiology -- Periodicals; Respiratory infections -- Microbiology -- Periodicals; Mouth -- Diseases -- Immunological aspects -- Periodicals; 617.522
• DOI: 10.1111/omi.12046
• Languages: English
• ISSNs: 2041-1006

Abstract

<abstract abstract-type="main" id="omi12046-abs-0001"> <title>Summary</title> <p>Natural competence is the ability of bacteria to incorporate extracellular DNA into their genomes. This competence is affected by a number of factors, including Ca<sup>2+</sup> utilization and biofilm formation. As bacteria can form thick biofilms in the presence of extracellular Ca<sup>2+</sup>, the additive effects of Ca<sup>2+</sup>‐promoted biofilm formation on natural competence should be examined. We evaluated natural competence in <italic>Aggregatibacter actinomycetemcomitans</italic>, an important periodontal pathogen, in the context of Ca<sup>2+</sup>‐promoted biofilms, and examined whether the <italic>pga</italic> gene cluster, required for bacterial cell aggregation, is necessary for competence development. The <italic>A</italic>. <italic>actinomycetemcomitans</italic> cells grown in the presence of 1 m<sc>m</sc> CaCl<sub>2</sub> exhibited enhanced cell aggregation and increased levels of cell‐associated Ca<sup>2+</sup>. Biofilm‐derived cells grown in the presence of Ca<sup>2+</sup> exhibited the highest levels of natural transformation frequency and enhanced expression of the competence regulator gene, <italic>tfoX</italic>. Natural competence was enhanced by the additive effects of Ca<sup>2+</sup>‐promoted biofilms, in which high levels of <italic>pga</italic> gene expression were also detected. Mutation of the <italic>pga</italic> gene cluster disrupted biofilm formation and competence development, suggesting that these genes play a critical role in the ability of <italic>A</italic>. <italic>actinomycetemcomitans</italic> to adapt to its natural environment. The Ca<sup>2+</sup>‐promoted biofilms may enhance the ability of bacteria to acquire extracellular DNA.</p> </abstract>