Cobalamin riboswitch

Cobalamin riboswitch
Predicted secondary structure and sequence conservation of Cobalamin
Identifiers
Symbol	Cobalamin
Rfam	RF00174
Other data
RNA type	Cis-reg; riboswitch
Domain(s)	Bacteria
SO	0000035

Cobalamin riboswitch is a cis-regulatory element which is widely distributed in 5' untranslated regions of vitamin B₁₂ (Colbalamin) related genes in bacteria.^[1] Riboswitches are metabolite binding domains within certain messenger RNAs (mRNAs) that serve as precision sensors for their corresponding targets. Allosteric rearrangement of mRNA structure is mediated by ligand binding, and this results in modulation of gene expression or translation of mRNA to yield a protein. Cobalamin in the form of adenosylcobalamin (Ado-CBL) is known to repress expression of proteins for vitamin B₁₂ biosynthesis via a post-transcriptional regulatory mechanism that involves direct binding of Ado-CBL to 5' UTRs in relevant genes, preventing ribosome binding and translation of those genes. Before proof of riboswitch function, a conserved sequence motif called the B₁₂ box^[2] was identified that corresponds to a part of the cobalamin riboswitch,^[1] and a more complete conserved structure was identified.^[3][4] Variants of the riboswitch consensus have been identified.^[5]

References

1. ^ ^{a b} Nahvi A, Sudarsan N, Ebert MS, Zou X, Brown KL, Breaker RR (September 2002). "Genetic control by a metabolite binding mRNA". Chem. Biol. 9 (9): 1043. doi:10.1016/S1074-5521(02)00224-7. PMID 12323379. 
2. ^ Franklund CV, Kadner RJ (June 1997). "Multiple transcribed elements control expression of the Escherichia coli btuB gene". J. Bacteriol. 179 (12): 4039–42. PMC 179215. PMID 9190822. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=179215. 
3. ^ Vitreschak AG, Rodionov DA, Mironov AA, Gelfand MS (2003). "Regulation of the vitamin B₁₂ metabolism and transport in bacteria by a conserved RNA structural element". RNA 9 (9): 1084–97. doi:10.1261/rna.5710303. PMC 1370473. PMID 12923257. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1370473. 
4. ^ Barrick JE, Breaker RR (2007). "The distributions, mechanisms, and structures of metabolite-binding riboswitches". Genome Biol. 8 (11): R239. doi:10.1186/gb-2007-8-11-r239. PMC 2258182. PMID 17997835. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2258182. 
5. ^ Weinberg Z, Wang JX, Bogue J, et al. (March 2010). "Comparative genomics reveals 104 candidate structured RNAs from bacteria, archaea and their metagenomes". Genome Biol 11 (3): R31. doi:10.1186/gb-2010-11-3-r31. PMC 2864571. PMID 20230605. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2864571. 

External links

• Rfam page for Cobalamin riboswitch