SAM-V riboswitch
SAM-V riboswitch is the fifth known riboswitch to bind S-adenosyl methionine (SAM). It was first discovered in the marine organism Candidatus Pelagibacter ubique and can also be found in marine metagenomes.[1] SAM-V features a similar consensus sequence and secondary structure as the binding site of SAM-II riboswitch, but bioinformatics scans cluster the two aptamers independently. These similar binding pockets suggest that the two riboswitches have undergone convergent evolution.[2]
SAM-binding was confirmed using equilibrium dialysis. The riboswitch has been characterised as a 'tandem riboswitch' - it is able to regulate both translation and transcription. When SAM is present in high concentration, SAM-II will bind its ligand and form a terminator stem to halt transcription. If SAM exists in lower concentrations, SAM-V will be transcribed and, if SAM concentration should then increase, it can bind SAM and occlude the Shine-Dalgarno sequence of the downstream open reading frame. This regulation controls parts of the sulfur metabolism of marine bacteria.[2]
See also
References
Further reading
- Kazanov MD, Vitreschak AG, Gelfand MS (2007). "Abundance and functional diversity of riboswitches in microbial communities". BMC Genomics 8: 347. doi:10.1186/1471-2164-8-347. PMC 2211319. PMID 17908319. http://www.biomedcentral.com/1471-2164/8/347. Retrieved 2010-08-26.
- Zhu Y, Pulukkunat DK, Li Y (2007). "Deciphering RNA structural diversity and systematic phylogeny from microbial metagenomes". Nucleic Acids Res. 35 (7): 2283–94. doi:10.1093/nar/gkm057. PMC 1874661. PMID 17389640. http://nar.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=17389640. Retrieved 2010-08-26.
- Winkler WC, Breaker RR (2005). "Regulation of bacterial gene expression by riboswitches". Annu. Rev. Microbiol. 59: 487–517. doi:10.1146/annurev.micro.59.030804.121336. PMID 16153177. http://arjournals.annualreviews.org/doi/full/10.1146/annurev.micro.59.030804.121336?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dncbi.nlm.nih.gov. Retrieved 2010-08-26.
- Mandal M, Lee M, Barrick JE, et al. (October 2004). "A glycine-dependent riboswitch that uses cooperative binding to control gene expression". Science 306 (5694): 275–9. doi:10.1126/science.1100829. PMID 15472076. http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=15472076. Retrieved 2010-08-26.
- Yooseph S, Sutton G, Rusch DB, et al. (March 2007). "The Sorcerer II Global Ocean Sampling expedition: expanding the universe of protein families". PLoS Biol. 5 (3): e16. doi:10.1371/journal.pbio.0050016. PMC 1821046. PMID 17355171. http://dx.plos.org/10.1371/journal.pbio.0050016. Retrieved 2010-08-26.
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