THE ESCHERICHIA-COLI OXYS REGULATORY RNA REPRESSES FHLA TRANSLATION BY BLOCKING RIBOSOME BINDING

OxyS is a small untranslated RNA which is induced in response to oxida tive stress in Escherichia coli. This novel RNA acts as a global regul ator to activate or repress the expression of as many as 40 genes, inc luding the fhlA-encoded transcriptional activator and the rpoS-encoded sigma(S) subunit of RNA polymerase. Deletion analysis of OxyS showed that different domains of the small RNA are required for the regulatio n of fhlA and rpoS, We examined the mechanism of OxyS repression of fh lA and found that the OxyS RNA inhibits fhlA translation by pairing wi th a short sequence overlapping the Shine-Dalgarno sequence, thereby b locking ribosome binding/translation.