Related Experiment Video

Updated: Jan 10, 2026

PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions
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PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions

Published on: July 27, 2017

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Phospholipid-independent biogenesis of a functional RP4 conjugation pilus

Naito Ishimoto1,2, Shan He1, Mikhail Bogdanov3

  • 1Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.

Biorxiv : the Preprint Server for Biology
|November 24, 2025
PubMed

Insights

Researchers discovered the RP4 pilus, a lipid-independent bacterial conjugation structure. This finding challenges the essential role of lipids in mating pair formation (MPF) and expands understanding of bacterial DNA transfer mechanisms.

Area of Science:

  • Microbiology
  • Structural Biology
  • Molecular Biology

Background:

  • Bacterial conjugation relies on mating pair formation (MPF) initiated by conjugative pili.
  • IncP RP4 plasmid conjugation involves short, rigid mating pili.

Purpose of the Study:

  • To determine the cryo-EM structure of the RP4 pilus.
  • To investigate the role of lipid modification in pilus formation and function.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) at 2.75 Å resolution.
  • Quantitative mass spectral analysis.
  • Analysis of *E. coli pgsA* mutant strains.

Main Results:

  • The RP4 pilus structure revealed non-lipidated cyclic TrbC pilin subunits.
  • RP4 conjugation occurs in *E. coli pgsA* mutants lacking phosphatidylglycerol (PG).
  • R27 plasmid conjugation, dependent on PG-associated pilin subunits (TrhA), fails in these mutants.

Conclusions:

  • The RP4 pilus is the first identified lipid-independent functional mating pilus.
  • Challenges the necessity of lipid moieties for conjugative pilus construction and MPF.
  • Expands understanding of bacterial genetic material transfer mechanisms.
Keywords:
conjugative piluscyclizationlipid-independent pilus biogenesismating pair formationphosphatidylglycerolphospholipids

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