Riboregulation in Escherichia coli : DsrA RNA acts by RNA:RNA interactions at multiple loci

Riboregulation in Escherichia coli: DsrA RNA acts by RNA:RNA interactions at multiple loci

Molecular Genetics Program, Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, P.O. Box 22002, Albany, New York 12201-2002

Edited by Sidney Altman, Yale University, New Haven, CT, and approved July 16, 1998 (received for review May 18, 1998)

Abstract

DsrA is an 87-nt untranslated RNA that regulates both the global transcriptional silencer and nucleoid protein H-NS and the stationary phase and stress response sigma factor RpoS (σ^s). We demonstrate that DsrA acts via specific RNA:RNA base pairing interactions at the hns locus to antagonize H-NS translation. We also give evidence that supports 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 expression that acts coordinately via RNA:RNA interactions at multiple loci.