A New Sugar for an Old Phage: a c-di-GMP-Dependent Polysaccharide Pathway Sensitizes <i>Escherichia coli</i> for Bacteriophage Infection
Benjamin Sellner, Rūta Prakapaitė, Margo Berkum, Matthias Heinemann, Alexander Harms, Urs Jenal
Abstract
Because bacterial surface glycans are in direct contact with the environment they can provide essential protective functions during infections or against competing bacteria. But such structures are also "Achilles' heels" since they can serve as primary receptors for bacteriophages. Bacteria thus need to carefully control the exposure of conserved surface glycans to balance costs and benefits. Here, we identify a novel exopolysaccharide that is widely conserved in E. coli and is used by N4 and related bacteriophages as primary receptor. We demonstrate that the synthesis of NGR (N4 glycan receptor) is tightly controlled by the second messenger c-di-GMP in a highly specific manner and by a single diguanylate cyclase. These studies provide an example of how bacteria can alleviate the strong selective pressure imposed on them by bacteriophages entering through conserved surface structures by carefully regulating their synthesis and secretion.