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Updated: Sep 23, 2025

Time-lapse Imaging of Bacterial Swarms and the Collective Stress Response
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Atomic-scale interactions between quorum sensing autoinducer molecules and the mucoid P. aeruginosa exopolysaccharide

Oliver J Hills1, Chin W Yong2,3, Andrew J Scott4

  • 1School of Food Science & Nutrition, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK. fsojh@leeds.ac.uk.

Scientific Reports
|May 11, 2022
PubMed

Insights

Mucoid Pseudomonas aeruginosa biofilms in cystic fibrosis lungs are resistant to antibiotics. New molecular dynamics simulations reveal how signaling molecules interact with the biofilm matrix, identifying PQS as a potential target for new therapies.

Area of Science:

  • Microbiology
  • Biophysics
  • Computational Chemistry

Background:

  • Mucoid Pseudomonas aeruginosa forms antibiotic-resistant biofilms in cystic fibrosis lungs.
  • Biofilm matrix (exopolysaccharide) hinders antimicrobial diffusion and bacterial communication.
  • Quorum sensing autoinducers (QSAIs) regulate biofilm chronicity and virulence but their interaction with the matrix is unclear.

Purpose of the Study:

  • To investigate the atomic-level interactions between key QSAIs (C4-HSL and PQS) and the calcium-crosslinked exopolysaccharide (EPS) matrix.
  • To understand the molecular mechanisms governing QSAI passage through the EPS biofilm.
  • To identify potential targets for disrupting P. aeruginosa biofilm.

Main Methods:

  • Employed a combined molecular dynamics (MD) and density functional theory (DFT) approach.
  • Developed a large-scale, calcium-crosslinked, multi-chain EPS molecular model.
  • Used MD to simulate physiological equilibrium interactions and DFT to calculate thermodynamic stability of QSAI-EPS complexes.

Main Results:

  • Provided a thermodynamic explanation for the observed mobility of C4-HSL within the EPS.
  • Identified specific molecular features of the EPS responsible for binding QSAIs.
  • Demonstrated significantly reduced mobility for PQS within the EPS matrix compared to C4-HSL.

Conclusions:

  • The study elucidates the molecular interactions between Pseudomonas aeruginosa quorum sensing autoinducers and the exopolysaccharide biofilm matrix.
  • Findings explain the differential mobility of QSAIs within the biofilm.
  • Suggests PQS is a promising target for quorum quenching strategies to combat chronic P. aeruginosa infections in cystic fibrosis.

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