The extracellular DNA lattice of bacterial biofilms is structurally related to Holliday junction recombination intermediates

Abstract

Extracellular DNA (eDNA) is a critical component of the extracellular matrix of bacterial biofilms that protects the resident bacteria from environmental hazards which includes imparting significantly greater resistance to antibiotics and host immune effectors. eDNA is organized into a lattice-like structure, stabilized by the DNABII family of proteins, known to have high affinity and specificity for HJs. Accordingly, we demonstrated that the branched eDNA structures present within the biofilms formed by NTHI in the middle ear of the chinchilla in an experimental otitis media model, and in sputum samples that contain multiple mixed bacterial species and were recovered from cystic fibrosis (CF) patients possess a HJ-like configuration. Next, we showed that the prototypic E. coli HJ-specific DNA-binding protein RuvA could be functionally exchanged for DNABII proteins in the stabilization of biofilms formed by three diverse human pathogens, UPEC, NTHI and Staphylococcus epidermidis. Importantly, while replacement of DNABII proteins within the NTHI biofilm matrix with RuvA was shown to retain similar mechanical properties when compared to the control NTHI biofilm structure, we also demonstrated that biofilm eDNA matrices stabilized by RuvA could be subsequently undermined upon addition of the HJ resolvase complex, RuvABC, which resulted in significant biofilm disruption. Collectively, our data suggested that nature has recapitulated a functional equivalent of the HJ recombination intermediate to maintain the structural integrity of bacterial biofilms.

More information

Identifiers

ORCID for Paul Stoodley: orcid.org/0000-0001-6069-273X

Catalogue record

Export record

Altmetrics