Porin self-association enables cell-to-cell contact in Providencia stuartii floating communities

Proc Natl Acad Sci U S A. 2018 Mar 6;115(10):E2220-E2228. doi: 10.1073/pnas.1714582115. Epub 2018 Feb 23.


The gram-negative pathogen Providencia stuartii forms floating communities within which adjacent cells are in apparent contact, before depositing as canonical surface-attached biofilms. Because porins are the most abundant proteins in the outer membrane of gram-negative bacteria, we hypothesized that they could be involved in cell-to-cell contact and undertook a structure-function relationship study on the two porins of P. stuartii, Omp-Pst1 and Omp-Pst2. Our crystal structures reveal that these porins can self-associate through their extracellular loops, forming dimers of trimers (DOTs) that could enable cell-to-cell contact within floating communities. Support for this hypothesis was obtained by studying the porin-dependent aggregation of liposomes and model cells. The observation that facing channels are open in the two porin structures suggests that DOTs could not only promote cell-to-cell contact but also contribute to intercellular communication.

Keywords: biofilms; cell adhesion; intercellular communication; porins; steric zippers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Outer Membrane Proteins / metabolism
  • Biofilms*
  • Crystallography, X-Ray
  • Dimerization
  • Porins / chemistry
  • Porins / genetics
  • Porins / metabolism*
  • Providencia / chemistry
  • Providencia / genetics
  • Providencia / physiology*


  • Bacterial Outer Membrane Proteins
  • Porins

Associated data

  • PDB/4d64
  • PDB/5nxr
  • PDB/5nxu
  • PDB/4d65
  • PDB/5n9i
  • PDB/5n9h
  • PDB/5nxn