A small RNA acts as an antisilencer of the H-NS-silenced rcsA gene of Escherichia coli.
The regulation of capsular polysaccharide synthesis in Escherichia coli K-12 depends on the level of an unstable positive regulator, RcsA. The amount of RcsA protein is limited both by its rapid degradation by Lon, an ATP-dependent protease, and by its low level of synthesis. We have found that the low level of expression from the rcsA promoter is due to transcriptional silencing by the histone-like protein H-NS; this silencing is sensitive to both sequence and context in a region upstream of the -35 region of the promoter. A small (85-nt) RNA, DsrA, when overproduced, activates transcription of rcsA::lacZ fusions by counteracting H-NS silencing. DsrA RNA does not show any extended homology with the rcsA promoter or other sequenced regions of E. coli. Since the stimulation of rcsA transcription by this small RNA does not depend on any sequences from within the rcsA transcript, DsrA acts, either directly or indirectly, on rcsA transcription initiation.
Sledjeski
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Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255.
Gottesman
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D049069:ATP-Dependent Proteases; D000251:Adenosine Triphosphatases / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015870:Gene Expression; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000235:genetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D049070:Protease La; D012315:RNA Caps / Q000378:metabolism; D012329:RNA, Bacterial / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D012697:Serine Endopeptidases / Q000378:metabolism; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D006360:Heat-Shock Proteins; D012315:RNA Caps; D012329:RNA, Bacterial; D011993:Recombinant Fusion Proteins; C067572:RcsA protein, E coli; D001616:beta-Galactosidase; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La; D000251:Adenosine Triphosphatases