RT Journal Article SR Electronic T1 A novel locally c-di-GMP-controlled exopolysaccharide synthase required for N4 phage infection of E. coli JF bioRxiv FD Cold Spring Harbor Laboratory SP 2021.10.01.462733 DO 10.1101/2021.10.01.462733 A1 Eike H. Junkermeier A1 Regine Hengge YR 2021 UL http://biorxiv.org/content/early/2021/10/01/2021.10.01.462733.abstract AB A major target of c-di-GMP signaling is the production of biofilm-associated extracellular polymeric substances (EPS), which in Escherichia coli K-12 include amyloid curli fibres, phosphoethanolamine-modified (pEtN-)cellulose and poly-N-acetyl-glucosamine (PGA). However, the characterized c-di-GMP-binding effector systems are largely outnumbered by the 12 diguanylate cyclases (DGCs) and 13 phosphodiesterases (PDEs), which synthetize and degrade c-di-GMP, respectively. E. coli possesses a single protein with a potentially c-di-GMP-binding MshEN domain, NfrB, which – together with the outer membrane protein NfrA – is known to serve as a receptor system for phage N4. Here, we show that NfrB not only binds c-di-GMP with high affinity, but as a novel c-di-GMP-controlled glycosyltransferase synthesizes a secreted EPS, which can impede motility and is required as an initial receptor for phage N4 infection. In addition, a systematic screening of the 12 DGCs of E. coli K-12 revealed that specifically DgcJ is required for the infection with phage N4 and interacts directly with NfrB. This is in line with local signaling models, where specific DGCs and/or PDEs form protein complexes with particular c-di-GMP effector/target systems. Our findings thus provide further evidence that intracellular signaling pathways, which all use the same diffusible second messenger, can act in parallel in a highly specific manner.Importance Key findings in model organisms led to the concept of ‘local’ signaling, challenging the dogma of a gradually increasing global intracellular c-di-GMP concentration driving the motile-sessile transition in bacteria. In our current model, bacteria dynamically combine global as well as local signaling modes, in which specific DGCs and/or PDEs team up with effector/target systems in multiprotein complexes. Our present study highlights a novel example of how specificity in c-di-GMP signaling can be achieved by showing NfrB as a novel c-di-GMP binding effector in E. coli, which is controlled in a local manner specifically by DgcJ. We further show that NfrB (which was initially found as a part of a receptor system for phage N4) is involved in the production of a novel exopolysaccharide. Finally, our data shine new light on host interaction of phage N4, which uses this exopolysaccharide as an initial receptor for adsorption.Competing Interest StatementThe authors have declared no competing interest.