The small RNA, DsrA, is essential for the low temperature expression of RpoS during exponential growth in Escherichia coli.

Sledjeski, Darren D.; Gupta, Alka; Gottesman, Susan

doi:10.1002/j.1460-2075.1996.tb00773.x

Cited by 337 publications

(382 citation statements)

References 41 publications

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“…Because DsrA is the predominant ncRNA involved in the translational regulation of rpoS at low temperatures, all assays were conducted at 30 °C (ref. 44). To prevent overexpression of Hfq, the mutants were expressed under control of the inducible araBAD promoter 45 .…”

Section: Accumulation and Complementation Analysis Of Hfq Mutantsmentioning

confidence: 99%

Escherichia coli Hfq has distinct interaction surfaces for DsrA, rpoS and poly(A) RNAs

Mikulecky

Kaw

Brescia

et al. 2004

Nat Struct Mol Biol

225

395

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The bacterial Sm-like protein Hfq facilitates RNA-RNA interactions involved in posttranscriptional regulation of the stress response. Specifically, Hfq helps pair noncoding RNAs (ncRNAs) with complementary regions of target mRNAs. To probe the mechanism of this pairing, we generated a series of Hfq mutants and measured their affinity for RNAs like those with which Hfq must associate in vivo. We tested the mutants' DsrA-dependent activation of rpoS, and their ability to stabilize DsrA ncRNA against degradation in vivo. Our results suggest that Hfq has two independent RNA-binding surfaces. In addition to a well-known site around the core of the Hfq hexamer, we observe interactions with the distal face of Hfq, a new locus with which mRNAs and poly(A) sequences associate. Our model explains how Hfq can simultaneously bind a ncRNA and its mRNA target to facilitate the strand displacement reaction required for Hfq-dependent translational regulation.Hfq protein from Escherichia coli was first described in connection with Qβ-phage replication 1,2 . Hfq has recently emerged as a central player in post-transcriptional gene regulation as mediated by bacterial ncRNAs [3][4][5][6] . Escherichia coli Hfq mutants show disrupted signaling in stress response pathways 7,8 , arising from the need for Hfq to mediate base-pairing between regulatory ncRNAs and their mRNA targets. Examples of these partnerships include DsrA-rpoS 7,9,10 , OxyS-fhlA 11,12 , OxyS-rpoS 13 , RprA-rpoS 14 , RyhBsodB [15][16][17] .Complexes between ncRNAs and their mRNA targets function in several ways. Most commonly, complexed structures lead to translational activation or repression by remodeling mRNA regulatory regions containing the ribosome-binding site (RBS) and/or start codon. Alternatively, the interaction can enhance decay of the target mRNA16 or simply block translation11. Clearly, Hfq facilitates base-pairing between ncRNAs and their targets, but how it does so is poorly understood. How the chaperone function relates to other Hfq activities such as the control of poly(A) tail elongation19 , 20 and regulation of mRNA stability21 , 22 is also unknown. COMPETING INTERESTS STATEMENTThe authors declare that they have no competing financial interests. NIH Public Access Author ManuscriptNat Struct Mol Biol. Author manuscript; available in PMC 2011 April 5. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptHfq shares sequence similarity to the eukaryotic Lsm proteins [23][24][25][26][27] We addressed these questions through a mutational analysis of Hfq, probing in vitro binding to several model RNAs that represent species with which Hfq must interact. Hfq mutants were assayed in vivo using a reporter assay and RNA lifetime experiments. Together, the results support a model wherein at least two independent RNA-binding sites exist on the Hfq hexamer, and juxtaposition of bound RNAs facilitates base-pairing. RESULTS Hfq mutagenesisTo identify amino acids essential for RNA binding, we constructed a series of E. coli Hfq misse...

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Section: Accumulation and Complementation Analysis Of Hfq Mutantsmentioning

confidence: 99%

Escherichia coli Hfq has distinct interaction surfaces for DsrA, rpoS and poly(A) RNAs

Mikulecky

Kaw

Brescia

et al. 2004

Nat Struct Mol Biol

225

395

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“…HF-1, the small RNA-binding protein encoded by hfq, is required for efficient translation of the rpoS mRNA (Muffler et al, 1996;Brown and Elliott, 1996). dsrA, a small untranslated RNA, is required for expression of S at low temperature (Sledjeski et al, 1996). Curiously, overproduction of HF-1 protein complemented an hns mutation restoring repression of a single gene (i.e.…”

Section: Modulation Of Rpos Expressionmentioning

confidence: 99%

H‐NS: a modulator of environmentally regulated gene expression

Atlung

Ingmer

1997

Molecular Microbiology

453

409

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SummaryH-NS is a small chromatin-associated protein found in enterobacteria. H-NS has affinity for all types of nucleic acids but binds preferentially to intrinsically curved DNA. The major role of H-NS is to modulate the expression of a large number of genes, mostly by negatively affecting transcription. Many of the H-NS-modulated genes are regulated by environmental signals, and expression of most of these genes is positively regulated by specific transcription factors. Therefore one of the purposes of H-NS could be to repress expression of some genes under conditions characteristic of a non-intestinal environment, but allow expression of specific genes in response to certain stimuli in the intestinal environment. The hns gene is autoregulated. In vivo the H-NS to DNA ratio is fairly constant except during cold shock, when it increases threeto fourfold. In this review we propose that only the preferential binding to intrinsically curved DNA plays a role under normal growth conditions, and we discuss the different mechanisms by which H-NS might affect gene expression and how H-NS could be involved in the response to different stress situations. Finally, we summarize the evolutionary and functional relationship between H-NS and the homologous StpA.

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“…Translation is stimulated by osmotic upshift, i.e. by the addition of NaCl or sucrose (Muffler et al, 1996a), temperature downshift (Sledjeski et al, 1996) and during late exponential phase above a certain cell density, when cells are grown in minimal medium (Lange and Hengge-Aronis, 1994). S proteolysis is more or less strongly inhibited in response to starvation (Lange and Hengge-Aronis, 1994;Takayanagi et al, 1994), high osmolarity (Muffler et al, 1996a), heat shock (Muffler et al, 1997a) and, probably, shift to acid pH (Bearson et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

The LysR‐like regulator LeuO in Escherichia coli is involved in the translational regulation of rpoS by affecting the expression of the small regulatory DsrA‐RNA

Klauck

Böhringer

Hengge‐Aronis

1997

Molecular Microbiology

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SummaryThe translation of rpoS, which encodes the general stress sigma factor, S , in Escherichia coli, is stimulated by various stress conditions. Regulatory factors involved in this control are the RNA-binding Hfq (HF-I) protein, the histone-like protein H-NS and the small regulatory DsrA-RNA (with the last being specifically required for increased rpoS translation at low temperature). Here, we report the characterization of a transposon insertion mutant (Tn10-8) with reduced S levels that led to the identification of an additional factor involved in the regulation of rpoS translation, the LysR-like regulator LeuO.

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The small RNA, DsrA, is essential for the low temperature expression of RpoS during exponential growth in Escherichia coli.

Cited by 337 publications

References 41 publications

Escherichia coli Hfq has distinct interaction surfaces for DsrA, rpoS and poly(A) RNAs

Escherichia coli Hfq has distinct interaction surfaces for DsrA, rpoS and poly(A) RNAs

H‐NS: a modulator of environmentally regulated gene expression

The LysR‐like regulator LeuO in Escherichia coli is involved in the translational regulation of rpoS by affecting the expression of the small regulatory DsrA‐RNA

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