RIBOREGULATION IN ESCHERICHIA-COLI - DSRA RNA ACTS BY RNA-RNA INTERACTIONS AT MULTIPLE LOCI

DsrA is an 87-nt untranslated RNA that regulates both the global trans criptional silencer and nucleoid protein II-NS and the stationary phas e and stress response sigma factor RpoS (sigma(s)). We demonstrate tha t DsrA acts via specific RNA:RNA base pairing interactions at the hns locus to antagonize H-NS translation. We also give evidence that suppo rts a role for RNA:RNA interactions at the rpoS locus to enhance RpoS translation. Negative regulation of hns by DsrA is achieved by the RNA :RNA interaction blocking translation of hns RNA, In contrast, results suggest that positive regulation of rpoS by DsrA occurs by formation of an RNA structure that activates a cis-acting translational operator . Sequences within DsrA complementary to three additional genes, argR, ilvIH, and rbsD, suggest that DsrA is a riboregulator of gene express ion that acts coordinately via RNA:RNA interactions at multiple loci.