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PilF is an outer membrane lipoprotein required for multimerization and localization of the Pseudomonas aeruginosa

Jason Koo1, Stephanie Tammam, Shao-Yang Ku

  • 1Department of Biochemistry, University of Toronto, Program in Molecular Structure and Function, The Hospital for Sick Children, 555 University Avenue, Toronto M5G 1X8, ON, Canada.

Journal of Bacteriology
|September 9, 2008
PubMed

Insights

PilF, a Pseudomonas aeruginosa lipoprotein, is crucial for Type IV pili (T4P) assembly and function. Its outer membrane localization ensures proper secretin (PilQ) assembly, essential for T4P biogenesis and bacterial virulence.

Area of Science:

  • Microbiology
  • Structural Biology
  • Bacterial Pathogenesis

Background:

  • Type IV pili (T4P) are essential virulence factors in bacterial pathogens like Pseudomonas aeruginosa.
  • PilF is a lipoprotein critical for T4P biogenesis, but its precise role in secretin assembly and localization is not fully understood.

Purpose of the Study:

  • To elucidate the function of PilF in T4P biogenesis and PilQ secretin assembly.
  • To investigate the structural basis of PilF-PilQ interactions and the importance of PilF lipidation.

Main Methods:

  • Phenotypic characterization of a pilF mutant and a lipidation site mutant.
  • Cellular fractionation studies to determine protein localization.
  • X-ray crystallography to determine the structure of PilF.

Main Results:

  • PilF is an outer membrane pilotin essential for PilQ localization and multimerization, thereby enabling T4P assembly.
  • Mutation of the PilF lipidation site disrupts outer membrane tethering, leading to aberrant PilQ assembly and reduced piliation.
  • The 2.0-Å structure of PilF reveals tetratricopeptide repeats potentially involved in PilQ interaction.

Conclusions:

  • PilF's tethering to the outer membrane is critical for correct PilQ localization and stable T4P formation.
  • PilF structure provides insights into its mechanism of action in secretin assembly during T4P biogenesis.

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