Z-form extracellular DNA is a structural component of the bacterial biofilm matrix

Biofilms are community architectures adopted by bacteria inclusive of a self-formed extracellular matrix that protects resident bacteria from diverse environmental stresses and, in many species, incorporates extracellular DNA (eDNA) and DNABII proteins for structural integrity throughout biofilm development. Here, we present evidence that this eDNA-based architecture relies on the rare Z-form. Z-form DNA accumulates as biofilms mature and, through stabilization by the DNABII proteins, confers structural integrity to the biofilm matrix. Indeed, substances known to drive B-DNA into Z-DNA promoted biofilm formation whereas those that drive Z-DNA into B-DNA disrupted extant biofilms. Importantly, we demonstrated that the universal bacterial DNABII family of proteins stabilizes both bacterial-and host-eDNA in the Z-form in situ. A model is proposed that incorporates the role of Z-DNA in biofilm pathogenesis, innate immune response, and immune evasion.

Automated summary

Biofilms formed by bacteria rely on a rare Z-form DNA structure containing eDNA and DNABII proteins for structural integrity. Stabilization of Z-DNA by DNABII proteins promotes biofilm formation and stability, while disruption of Z-DNA structure can disturb existing biofilms. The universal bacterial DNABII family of proteins is shown to stabilize both bacterial and host eDNA in the Z-form, suggesting a role in biofilm pathogenesis and immune interactions.