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Expression of Kingella kingae type IV pili is regulated by sigma54, PilS, and PilR

Thomas E Kehl-Fie1, Eric A Porsch, Sara E Miller

  • 1Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.

Journal of Bacteriology
|May 26, 2009
PubMed

Insights

Kingella kingae uses type IV pili for adherence, but their expression is complex. Genes like rpoN and pilR are crucial for pilus production, while pilS influences it, suggesting intricate regulation.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Bacterial Pathogenesis

Background:

  • Kingella kingae is an emerging pathogen causing serious infections in children.
  • Type IV pili in K. kingae mediate adherence to host cells and are downregulated during invasive disease.

Purpose of the Study:

  • To investigate the genetic regulation of type IV pilus expression in Kingella kingae.
  • To identify key genes and regulatory mechanisms controlling pilus production in K. kingae strain 269-492.

Main Methods:

  • Genomic analysis to identify homologs of pilus regulatory genes (rpoN, pilS, pilR).
  • Gene disruption experiments to assess the impact on pilus expression (pilA1 transcript levels, piliation).
  • Analysis of pilA1 promoter mutations and gel shift assays to determine transcription factor binding.

Main Results:

  • Disruption of rpoN or pilR significantly reduced pilA1 transcript and eliminated piliation.
  • Disruption of pilS caused a partial reduction in pilA1 transcript and piliation, affecting colony variants.
  • Sigma(54) and PilR directly bind to the pilA1 promoter, indicating transcriptional control.

Conclusions:

  • Type IV pilus expression in K. kingae is regulated by a complex, multilayered system involving rpoN, pilR, and pilS.
  • Regulation is influenced by both the bacterium's genetic makeup and environmental signals.
  • Understanding these regulatory mechanisms is crucial for deciphering K. kingae's pathogenesis.

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