S-adenosyl-L-homocysteine riboswitch
Predicted secondary structure and sequence conservation of SAH_riboswitch
Identifiers
SymbolSAH_riboswitch
RfamRF01057
Other data
RNA typeCis-reg; riboswitch
Domain(s)Bacteria
SOSO:0005836
PDB structuresPDBe

SAH riboswitches are a kind of riboswitch that bind S-adenosylhomocysteine (SAH).[1] When the coenzyme S-adenosylmethionine (SAM) is used in a methylation reaction, SAH is produced. SAH riboswitches typically up-regulate genes involved in recycling SAH to create more SAM (or the metabolically related methionine). This is particularly relevant to cells, because high levels of SAH can be toxic.[2] Originally identified by bioinformatics,[3] SAH riboswitches are apparent in many species of bacteria, predominantly certain Pseudomonadota and Actinomycetota. The atomic-resolution 3-dimensional structure of an SAH riboswitch has been solved using X-ray crystallography.[4]

Consensus secondary structure of SAH riboswitches. Layout is similar to that used in a published depiction.[1] Three base pairs in this secondary structure were incorrectly predicted, while an additional base pair is missing, as revealed by an atomic-resolution tertiary structure.[4]

References

  1. 1 2 Wang JX, Lee ER, Morales DR, Lim J, Breaker RR (2008). "Riboswitches that Sense S-adenosylhomocysteine and Activate Genes Involved in Coenzyme Recycling". Mol. Cell. 29 (6): 691–702. doi:10.1016/j.molcel.2008.01.012. PMC 2712820. PMID 18374645.
  2. ↑ Ueland PM (1982). "Pharmacological and biochemical aspects of S-adenosylhomocysteine and S-adenosylhomocysteine hydrolase". Pharmacol. Rev. 34 (3): 223–253. PMID 6760211.
  3. ↑ Weinberg Z, Barrick JE, Yao Z, et al. (2007). "Identification of 22 candidate structured RNAs in bacteria using the CMfinder comparative genomics pipeline". Nucleic Acids Res. 35 (14): 4809–4819. doi:10.1093/nar/gkm487. PMC 1950547. PMID 17621584.
  4. 1 2 Edwards AL, Reyes FE, Héroux A, Batey RT (September 2010). "Structural basis for recognition of S-adenosylhomocysteine by riboswitches". RNA. 16 (11): 2144–2155. doi:10.1261/rna.2341610. PMC 2957054. PMID 20864509.
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