DsrA RNA is a
non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally imp ...
that regulates both
transcription
Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including:
Genetics
* Transcription (biology), the copying of DNA into RNA, often th ...
, by overcoming transcriptional silencing by the nucleoid-associated
H-NS protein, and
translation
Translation is the communication of the semantics, meaning of a #Source and target languages, source-language text by means of an Dynamic and formal equivalence, equivalent #Source and target languages, target-language text. The English la ...
, by promoting efficient translation of the stress sigma factor,
RpoS
The gene ''rpoS'' (RNA polymerase, sigma S, also called katF) encodes the sigma factor ''sigma-38'' (σ38, or RpoS), a 37.8 kD protein in ''Escherichia coli''. Sigma factors are proteins that regulate transcription (genetics), transcription in ...
.
These two activities of DsrA can be separated by mutation: the first of three
stem-loop
Stem-loops are nucleic acid Biomolecular structure, secondary structural elements which form via intramolecular base pairing in single-stranded DNA or RNA. They are also referred to as hairpins or hairpin loops. A stem-loop occurs when two regi ...
s of the 85
nucleotide
Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...
RNA
Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...
is necessary for RpoS translation but not for anti-H-NS action, while the second stem-loop is essential for antisilencing and less critical for RpoS translation. The third stem-loop, which behaves as a transcription terminator, can be substituted by the
trp transcription terminator without loss of either DsrA function. The sequence of the first stem-loop of DsrA is complementary with the upstream leader portion of RpoS messenger RNA, suggesting that pairing of DsrA with the RpoS message might be important for translational regulation. The structures of DsrA and DsrA/rpoS complex were studied by
NMR
Nuclear magnetic resonance (NMR) is a physical phenomenon in which atomic nucleus, nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near and far field, near field) and respond by producing ...
. The study concluded that the sRNA contains a dynamic conformational equilibrium for its second stem–loop which might be an important mechanism for DsrA to regulate the translations of its multiple target mRNAs.
There is evidence that DsrA RNA can self-assemble into nanostructures through antisense interactions of three self-complementary regions.
Targets of DsrA
There is experimental evidence to suggest that DsrA interacts with the protein-coding genes hns,
rbsD,
,
ilvI
and rpoS
via an
anti-sense mechanism.
DsrA folds into a structure with three
hairpins. The second of these (
nucleotides
Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...
23–60) binds to
Hfq.
References
Further reading
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External links
* {{Rfam, id=RF00014, name=DsrA RNA
sRNATarBase page for DsrA interactions with hnssRNATarBase page for DsrA interactions with rbsDsRNATarBase page for DsrA interactions with argRsRNATarBase page for DsrA interactions with ilvIsRNATarBase page for DsrA interactions with rpoS
Non-coding RNA