RprA RNA
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The RprA RNA gene encodes a 106
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 ...
regulatory
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 ...
. Translational regulation of the stationary phase sigma factor RpoS is mediated by the formation of a double-stranded RNA
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 ...
structure in the upstream region of the
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 ...
messenger RNA, occluding the translation initiation site. Clones carrying rprA (RpoS regulator RNA A) increased the translation of RpoS. As with DsrA, RprA is predicted to form three stem-loops. Thus, at least two small RNAs, DsrA and RprA, participate in the positive regulation of RpoS translation. RprA also appears to bind to the RpoS leader. RprA is non-essential. Wasserman ''et al.'' demonstrated that this RNA is bound by the
Hfq protein The Hfq protein (also known as HF-I protein) encoded by the ''hfq'' gene was discovered in 1968 as an ''Escherichia coli'' host factor that was essential for replication of the bacteriophage Qβ. It is now clear that Hfq is an abundant bacterial R ...
. Binding to Hfq alters the conformation of RprA. In the presence of Hfq the stability of RprA is influenced by the
osmolarity Osmotic concentration, formerly known as osmolarity, is the measure of solute concentration, defined as the number of osmoles (Osm) of solute per litre (L) of solution (osmol/L or Osm/L). The osmolarity of a solution is usually expressed as Osm/ ...
of the cell, this is dependent on the
endoribonuclease In biochemistry, an endoribonuclease is a class of enzyme which is a type of ribonuclease (an RNA cleaver), itself a type of endonuclease (a nucleotide cleaver). It cleaves either single-stranded or double-stranded RNA, depending on the enzyme. Ex ...
RNase E. It has been shown the RprA regulates the protein coding genes, called csgD, this protein encodes a stationary phase-induced
biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...
regulator and ydaM, which encodes a diguanylate cyclase involved in activating csgD transcription. These two target genes are repressed by RprA which results in regulation of
biofilm A biofilm is a Syntrophy, syntrophic Microbial consortium, community of microorganisms in which cell (biology), cells cell adhesion, stick to each other and often also to a surface. These adherent cells become embedded within a slimy ext ...
formation.


References


External links

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RprA entry in ncRNA database
Non-coding RNA {{molecular-cell-biology-stub