Getting Drugs through Small Pores: Exploiting the Porins Pathway in Pseudomonas aeruginosa

ACS Infect Dis. 2018 Oct 12;4(10):1519-1528. doi: 10.1021/acsinfecdis.8b00149. Epub 2018 Aug 8.


Understanding molecular properties of outer membrane channels of Gram-negative bacteria is of fundamental significance as they are the entry point of polar antibiotics into bacteria. Outer membrane proteomics revealed OccK8 (OprE) to be among the five most expressed substrate specific channels of the clinically important Pseudomonas aeruginosa. The high-resolution X-ray structure and electrophysiology highlighted a very narrow pore. However, experimental in vitro methods showed the transport of natural amino acids and antibiotics, among them ceftazidime. We used molecular dynamics simulations to reveal the importance of the physicochemical properties of ceftazidime in modulating the translocation through OccK8, proposing a structure-function relationship. As in general porins, the internal electric field favors the translocation of polar molecules by gainful energy compensation in the central constriction region. Importantly, the comparatively narrow OccK8 pore can undergo a substrate-induced expansion to accommodate relatively large-sized substrates.

Keywords: antibiotics transport; crystal structure; molecular simulations; outer membrane; porins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / metabolism*
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / classification
  • Bacterial Proteins / metabolism*
  • Ceftazidime / metabolism*
  • Cell Membrane Permeability
  • Crystallography, X-Ray
  • Gram-Negative Bacteria / metabolism*
  • Liposomes / metabolism
  • Membrane Potentials
  • Molecular Dynamics Simulation
  • Porins / chemistry
  • Porins / classification
  • Porins / metabolism*
  • Protein Structure, Secondary
  • Protein Transport
  • Pseudomonas aeruginosa / metabolism*
  • Static Electricity


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Liposomes
  • OprE protein, Pseudomonas
  • Porins
  • Ceftazidime