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The Francisella pathogenicity island

Francis E Nano1, Crystal Schmerk

  • 1Department of Biochemistry and Microbiology, PO Box 3055 STN CSC, University of Victoria, Victoria B.C. V8W 3P6 Canada. fnano@uvic.ca

Annals of the New York Academy of Sciences
|March 31, 2007
PubMed

Insights

The Francisella pathogenicity island (FPI) is crucial for virulence, with mutations causing significant attenuation. Most FPI genes are transcribed, but their protein functions and roles in type VI secretion systems remain largely uncharacterized.

Area of Science:

  • Microbiology
  • Genetics
  • Bacterial Pathogenesis

Background:

  • The Francisella pathogenicity island (FPI) is a conserved gene cluster in *Francisella* species, essential for virulence.
  • FPI genes are critical for intramacrophage growth and survival of *Francisella* bacteria.

Purpose of the Study:

  • To investigate the genetic organization, regulation, and functional roles of the Francisella pathogenicity island (FPI).
  • To explore the potential involvement of FPI-encoded proteins in type VI secretion systems.

Main Methods:

  • Comparative genomics to analyze FPI gene conservation across *Francisella* strains.
  • Genetic manipulation to create FPI gene mutants and assess virulence phenotypes.
  • Gene expression studies (mRNA analysis) and biochemical methods to detect FPI-encoded proteins.
  • Bioinformatics analysis to predict protein functions and identify potential secretion systems.

Main Results:

  • The FPI is duplicated in most sequenced *Francisella* genomes, with high conservation of 16 genes.
  • Mutations in FPI genes lead to significant attenuation in virulence and impaired intramacrophage growth.
  • FPI gene expression is regulated by MglA and iron concentration.
  • Despite high mRNA levels, few FPI-encoded proteins have been biochemically detected, and their functions are largely unknown.
  • Bioinformatics suggests some FPI proteins are part of a type VI secretion system.

Conclusions:

  • The Francisella pathogenicity island (FPI) is indispensable for *Francisella* virulence, impacting bacterial survival within host cells.
  • While FPI genes are actively transcribed, their protein products' functions and roles, particularly in type VI secretion, require further elucidation.

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