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H-NS plays a role in expression of Acinetobacter baumannii virulence features

Bart A Eijkelkamp1, Uwe H Stroeher, Karl A Hassan

  • 1School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia.

Infection and Immunity
|May 8, 2013
PubMed

Insights

Multidrug-resistant Acinetobacter baumannii infections are increasing. This study reveals that mutations in the H-NS protein disrupt its regulatory control, leading to enhanced virulence and altered gene expression in A. baumannii.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Pathogenesis

Background:

  • Acinetobacter baumannii is a significant clinical pathogen, with increasing multidrug-resistant strains.
  • Limited understanding exists regarding the molecular mechanisms driving A. baumannii pathogenesis.

Purpose of the Study:

  • To investigate the virulence characteristics of a hypermotile A. baumannii variant.
  • To identify the genetic basis for enhanced virulence and altered cellular properties.

Main Methods:

  • Comparative genomics of hypermotile and parental A. baumannii strains.
  • Analysis of cellular lipid composition and fatty acid profiles.
  • Transcriptome analysis to assess global gene expression changes.
  • Identification and characterization of mutations in the H-NS gene.

Main Results:

  • A hypermotile A. baumannii variant exhibited enhanced adherence to human pneumocytes and increased lethality in C. elegans.
  • Lipid analysis indicated changes in fatty acid composition correlating with altered hydrophobicity, adherence, and motility.
  • Genomic analysis revealed disruption of the hns gene (encoding histone-like nucleoid structuring protein) in the hypermotile variant.
  • Transcriptome analysis showed significant alterations in genes related to the autotransporter Ata, type VI secretion system, and type I pilus cluster.
  • A second independent hypermotile variant possessed a mutation within the DNA-binding region of H-NS.

Conclusions:

  • Loss of regulatory control by the H-NS protein is responsible for the observed phenotypic and transcriptomic changes in A. baumannii.
  • Mutations affecting H-NS function contribute to the enhanced virulence of A. baumannii.

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