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Updated: Apr 16, 2026

Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification
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Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification

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A lipoprotein partner for the Escherichia coli outer membrane protein TolC

Jim Horne1, Elise Kaplan1, Ben Jin1

  • 1Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.

Elife
|April 15, 2026
PubMed

Insights

The Escherichia coli lipoprotein YbjP interacts with the TolC outer membrane protein, mimicking lipid modifications found in other bacteria. This interaction, visualized by cryo-EM, may stabilize TolC but isn't essential for efflux activity.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • TolC is an outer membrane protein in Gram-negative bacteria, crucial for multi-drug efflux and protein secretion.
  • TolC homologues typically have an N-terminal lipid modification for membrane anchoring, absent in E. coli TolC.
  • The lipoprotein YbjP interacts with TolC's periplasmic surface, with its lipid moiety embedding in the membrane.

Purpose of the Study:

  • To elucidate the structural basis of YbjP interaction with E. coli TolC.
  • To investigate the role of YbjP in TolC function and membrane association.
  • To understand how YbjP mimics conserved lipid modifications in TolC homologues.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) to determine structures of tripartite pumps (MacA-MacB-TolC and AcrA-AcrB-TolC) complexed with YbjP.
  • In vitro and in vivo biochemical assays to assess YbjP-TolC interaction and efflux activity.

Main Results:

  • Cryo-EM structures reveal YbjP binding to the periplasmic surface of TolC in MacA-MacB-TolC and AcrA-AcrB-TolC complexes.
  • YbjP's N-terminal lipid moiety embeds in the outer membrane, mimicking conserved modifications.
  • The YbjP-TolC interaction occurs spontaneously but is not essential for efflux activity under standard conditions.

Conclusions:

  • YbjP acts as a functional mimic of the N-terminal lipid modification typically found on TolC homologues.
  • YbjP may play a role in stabilizing TolC's orientation and distribution within the outer membrane.
  • YbjP might influence the expression of specific transporters, including those for tryptophan and cyclic peptide toxins.
Keywords:
AcrABZ-TolCE. coliMacAB-TolCbiochemistrychemical biologylipoproteinmembrane protein assemblymolecular biophysicsmulti-drug efflux pumpstructural biology

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