The RprA RNA gene encodes a 106

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecule ...

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 im ...

. Translational regulation of the stationary phase sigma factor RpoS is mediated by the formation of a double-stranded RNA stem-loop 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 in bacteria. Sigma factors ca ...

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/L ...

of the cell, this is dependent on the

endoribonuclease An endoribonuclease is a ribonuclease endonuclease. It cleaves either single-stranded or double-stranded RNA, depending on the enzyme. Example includes both single proteins such as RNase III, RNase A, RNase T1, RNase T2 and RNase H and also com ...

RNase E Ribonuclease E is a bacterial ribonuclease that participates in the processing of ribosomal RNA (9S to 5S rRNA) and the chemical degradation of bulk cellular RNA. Cellular localization RNase E was suggested to be a part of the cell membrane pr ...

. It has been shown the RprA regulates the protein coding genes, called

csgD CsgD is a transcription and response regulator protein referenced to as the master modulator of bacterial biofilm development. In '' E. coli'' cells, CsgD is tasked with aiding the transition from planktonic cell motility to the stationary phase ...

, this protein encodes a stationary phase-induced

biofilm A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular ...

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

formation.

References

External links

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