MicA RNA

SraD RNA
Predicted secondary structure and sequence conservation of SraD
Identifiers
Symbol SraD
Alt. Symbols sraD
Rfam RF00078
Other data
RNA type Gene; sRNA
Domain(s) Bacteria
SO 0000655

The MicA RNA (also known as SraD) is a small non-coding RNA that was discovered in E. coli during a large scale screen.[1] Expression of SraD is highly abundant in stationary phase, but low levels could be detected in exponentially growing cells as well.

Function

This RNA binds the Hfq protein and regulates levels of gene expression by an antisense mechanism. It is known to target the OmpA gene in E. coli and occludes the ribosome binding site.[2] Under conditions of envelope stress, micA transcription is induced. MicA and RybB RNA transcription is under the control of the sigma factor sigma(E).[3][4] MicA is known to interact with the mRNA encoding the quorum sensing synthase homolog, LuxS in E.coli and both RNAs are processed by the double stranded RNA endonuclease, RNase III.[5] Based on its conservation, this is presumably the case in close relatives and may serve as a long elusive link between envelope stress and quorum sensing.

The PhoPQ two-component system is repressed by MicA. The RNA presumably pairs with the ribosomal binding site of phoP mRNA, thereby inhibiting translation. This links micA to cellular processes such as Mg(2+) transport, virulence, LPS modifications and resistance to antimicrobial peptides.[6][7]

In S. typhimurium MicA has been shown to be involved in biofilm formation.[8]

Site directed mutagensis has been used to construct mutated forms of MicA forms in order to investigate the RNA determinants important to its stability and function.[9] Each 'domain' investigated ( 5′linear domain, the structured region with two stem-loops, the A/U-rich sequence and the 3′ poly(U) tail) was altered without affecting the overall secondary structure of MicA however, each 'domain' was found to have a different impact on stability and the ability of MicA to regulate its multiple targets.[9]

References

  1. ↑ Argaman, L; Hershberg R; Vogel J; Bejerano G; Wagner EG; Margalit H; Altuvia S (2001). "Novel small RNA-encoding genes in the intergenic regions of Escherichia coli". Curr Biol 11 (12): 941–950. doi:10.1016/S0960-9822(01)00270-6. PMID 11448770.
  2. ↑ Udekwu KI, Darfeuille F, Vogel J, Reimegård J, Holmqvist E, Wagner EG (2005). "Hfq-dependent regulation of OmpA synthesis is mediated by an antisense RNA". Genes Dev. 19 (19): 2355–66. doi:10.1101/gad.354405. PMC 1240044. PMID 16204185.
  3. ↑ Udekwu KI, Wagner EG (2007). "Sigma E controls biogenesis of the antisense RNA MicA". Nucleic Acids Res. 35 (4): 1279–88. doi:10.1093/nar/gkl1154. PMC 1851643. PMID 17267407.
  4. ↑ Johansen J, Rasmussen AA, Overgaard M, Valentin-Hansen P (2006). "Conserved small non-coding RNAs that belong to the sigmaE regulon: role in down-regulation of outer membrane proteins". J. Mol. Biol. 364 (1): 1–8. doi:10.1016/j.jmb.2006.09.004. PMID 17007876.
  5. ↑ Udekwu, KI (Oct 2010). "Transcriptional and post-transcriptional regulation of the Escherichia coli luxS mRNA; involvement of the sRNA MicA". PLOS ONE 5 (10): e13449. doi:10.1371/journal.pone.0013449.
  6. ↑ Coornaert A, Lu A, Mandin P, Springer M, Gottesman S, Guillier M (2010). "MicA sRNA links the PhoP regulon to cell envelope stress.". Mol Microbiol 76 (2): 467–79. doi:10.1111/j.1365-2958.2010.07115.x. PMC 2925231. PMID 20345657.
  7. ↑ Coornaert, A; Chiaruttini, C; Springer, M; Guillier, M (January 2013). "Post-Transcriptional Control of the Escherichia coli PhoQ-PhoP Two-Component System by Multiple sRNAs Involves a Novel Pairing Region of GcvB.". PLOS Genetics 9 (1): e1003156. doi:10.1371/journal.pgen.1003156. PMC 3536696. PMID 23300478.
  8. ↑ Kint G, De Coster D, Marchal K, Vanderleyden J, De Keersmaecker SC (2010). "The small regulatory RNA molecule MicA is involved in Salmonella enterica serovar Typhimurium biofilm formation". BMC Microbiol. 10: 276. doi:10.1186/1471-2180-10-276. PMC 2987988. PMID 21044338.
  9. 1 2 Andrade, J. M.; Pobre, V. N.; Arraiano, C. L. M. (2013). Sumby, Paul, ed. "Small RNA Modules Confer Different Stabilities and Interact Differently with Multiple Targets". PLoS ONE 8 (1): e52866. doi:10.1371/journal.pone.0052866. PMC 3551931. PMID 23349691.

Further reading

External links


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