DNABII proteins play a central role in UPEC biofilm structure

Summary Most chronic and recurrent bacterial infections involve a biofilm component, the foundation of which is the extracellular polymeric substance ( EPS ). Extracellular DNA (e DNA ) is a conserved and key component of the EPS of pathogenic biofilms. The DNABII protein family includes integration host factor ( IHF ) and histone‐like protein ( HU ); both are present in the extracellular milieu. We have shown previously that the DNABII proteins are often found in association with e DNA and are critical for the structural integrity of bacterial communities that utilize e DNA as a matrix component. Here, we demonstrate that uropathogenic E scherichia coli ( UPEC ) strain UTI 89 incorporates e DNA within its biofilm matrix and that the DNABII proteins are not only important for biofilm growth, but are limiting; exogenous addition of these proteins promotes biofilm formation that is dependent on e DNA . In addition, we show that both subunits of IHF , yet only one subunit of HU ( HupB ), are critical for UPEC biofilm development. We discuss the roles of these proteins in context of the UPEC EPS .