exoRNA-mediated Cell-to-cell Communications in E. coli are Supported by Dps Mobility

Being a ferroxidase and a structural factor of the Escherichia coli nucleoid, Dps protein was recently encountered in the outer membrane and attracted attention as a potential partner for bacterial RNAs. Here, we show the first images visualizing Dps on the surface of bacteria and demonstrate that Dps produced by E. coli K-12 MG1655 or BL21(DE3) cells can cross bacteria-impermeable membrane and attach to the cell surface of a dps-null mutant. Using RNAseq and pull-down assays, we identified RNAs with specifically reduced secretion in the mutant and witnessed preferential interaction of Dps with tRNA and sRNA fragments. Upon analysis of their deviations from the genomic sequences, we selected one circular and six linear oligonucleotides with different folding as model RNAs and showed their ability to affect the growth of bacteria via Dps-dependent internalization by cells. This assumes Dps involvement in intercellular signal transduction within a bacterial population through participation in RNA secretion Secretion of E.coli RNAs in the presence or absence of Dps was studied using RNA-seq and pull-down assays