The biofilm matrix scaffold of Ps eudomonas aeruginosa contains G-quadruplex extracellular DNA structures

Thomas Seviour*, Fernaldo Richtia Winnerdy, Lan Li Wong, Xiangyan Shi, Sudarsan Mugunthan, Yong Hwee Foo, Remi Castaing, Sunil S. Adav, Sujatha Subramoni, Gurjeet Singh Kohli, Heather M. Shewan, Jason R. Stokes, Scott A. Rice, Anh Tuân Phan, Staffan Kjelleberg

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review


Extracellular DNA, or eDNA, is recognised as a critical biofilm component; however, it is not understood how it forms networked matrix structures. Here, we isolate eDNA from static-culture Pseudomonas aeruginosa biofilms using ionic liquids to preserve its biophysical signatures of fluid viscoelasticity and the temperature dependency of DNA transitions. We describe a loss of eDNA network structure as resulting from a change in nucleic acid conformation, and propose that its ability to form viscoelastic structures is key to its role in building biofilm matrices. Solid-state analysis of isolated eDNA, as a proxy for eDNA structure in biofilms, reveals non-canonical Hoogsteen base pairs, triads or tetrads involving thymine or uracil, and guanine, suggesting that the eDNA forms G-quadruplex structures. These are less abundant in chromosomal DNA and disappear when eDNA undergoes conformation transition. We verify the occurrence of G-quadruplex structures in the extracellular matrix of intact static and flow-cell biofilms of P. aeruginosa, as displayed by the matrix to G-quadruplex-specific antibody binding, and validate the loss of G-quadruplex structures in vivo to occur coincident with the disappearance of eDNA fibres. Given their stability, understanding how extracellular G-quadruplex structures form will elucidate how P. aeruginosa eDNA builds viscoelastic networks, which are a foundational biofilm property.

Original languageEnglish
Article number27
Journalnpj Biofilms and Microbiomes
Publication statusPublished - Dec 2021


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