Stress-induced toxic genomic R-loops support biofilm extracellular matrix formation

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Bacterial biofilms enhance antimicrobial resistance by forming protective extracellular polymeric matrices.
• Extracellular DNA (eDNA) is a key component of these biofilm matrices, contributing to their structure and function.

Purpose of the Study:

• To investigate the role of persistent R-loops in the viscoelastic properties of eDNA within Pseudomonas aeruginosa biofilms.
• To elucidate the mechanism of R-loop formation and their contribution to biofilm matrix development.

Main Methods:

• Analysis of R-loop structures in Pseudomonas aeruginosa biofilms.
• Investigating the role of RecA in R-loop formation.
• Studying the impact of R-loops on eDNA viscoelasticity and biofilm matrix formation.

Main Results:

• Persistent R-loops, DNA:RNA hybrids, were identified as significant contributors to the viscoelastic behavior of eDNA in P. aeruginosa biofilms.
• R-loops are formed via RecA-mediated trans-insertion of RNA strands, leading to genomic instability and programmed cell death.
• Released R-loops serve as essential building blocks for the viscoelastic extracellular matrix, benefiting the surviving bacterial population.

Conclusions:

• R-loops play a crucial role in establishing the viscoelastic eDNA matrix within bacterial biofilms under stress conditions.
• Targeting R-loop formation presents a promising therapeutic strategy for combating bacterial biofilm formation and enhancing antimicrobial susceptibility.