Sxy 5′ UTR element

The Sxy 5′ UTR element is an RNA element that controls expression of the sxy gene in H. influenzae. The sxy gene is a transcription factor (also known as TfoX) that regulates competence which is the ability of bacteria to take up DNA from their environment.[1] When the sxy gene is deleted the bacterium loses the ability to express genes in the competence regulon. Cameron et al. recently showed that mutations in the 5′ end of the sxy gene lead to hypercompetance.[2] They showed that this region formed an RNA secondary structure that occludes the Shine-Dalgarno sequence. Mutations that interfere with the stability of this secondary structure lead to increased translation of sxy followed by upregulation of the competence regulon.[2]

sxy 5′ UTR element
Secondary structure of the sxy 5′-UTR regulatory element
Identifiers
Symbolsxy
RfamRF00632
Other data
RNA typeCis-reg
Domain(s)Haemophilus influenzae
PDB structuresPDBe

tfoR RNA

In the fellow gammaproteobacterium Vibrio cholerae, a different RNA regulatory system is used.[3] Here, a sRNA named 'tfoR' positively regulates expression of the sxy (tfoX) protein.[4]

The RNA element responds to chitin, which is an important regulator of competence in V. cholera.[5] Deletion of tfoR removed all competence for exogenous DNA in V. cholera in vivo.[3]

References
  1. Redfield RJ (September 1991). "sxy-1, a Haemophilus influenzae mutation causing greatly enhanced spontaneous competence". J. Bacteriol. 173 (18): 5612–5618. PMC 208288. PMID 1653215.
  2. Cameron AD, Volar M, Bannister LA, Redfield RJ (January 2008). "RNA secondary structure regulates the translation of sxy and competence development in Haemophilus influenzae". Nucleic Acids Res. 36 (1): 10–20. doi:10.1093/nar/gkm915. PMC 2248739. PMID 17981840.
  3. Yamamoto, S; Morita, M; Izumiya, H; Watanabe, H (Jun 1, 2010). "Chitin disaccharide (GlcNAc)2 induces natural competence in Vibrio cholerae through transcriptional and translational activation of a positive regulatory gene tfoXVC". Gene. 457 (1–2): 42–49. doi:10.1016/j.gene.2010.03.003. PMID 20302923.
  4. Yamamoto, S; Izumiya, H; Mitobe, J; Morita, M; Arakawa, E; Ohnishi, M; Watanabe, H (Apr 2011). "Identification of a Chitin-Induced Small RNA That Regulates Translation of the tfoX Gene, Encoding a Positive Regulator of Natural Competence in Vibrio cholerae". Journal of Bacteriology. 193 (8): 1953–1965. doi:10.1128/JB.01340-10. PMC 3133033. PMID 21317321.
  5. Meibom, KL; Blokesch, M; Dolganov, NA; Wu, CY; Schoolnik, GK (Dec 16, 2005). "Chitin induces natural competence in Vibrio cholerae". Science. 310 (5755): 1824–1827. doi:10.1126/science.1120096. PMID 16357262.
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