SMK box riboswitch

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The SMK box riboswitch is an RNA element that regulates gene expression in bacteria.[1][2] The SMK box riboswitch is found in the 5' UTR of the MetK gene in lactic acid bacteria. The structure of this element changes upon binding to S-adenosyl methionine (SAM) to a conformation that blocks the shine-dalgarno sequence and blocks translation of the gene.

There are two other known SAM-binding riboswitches: SAM-I, SAM-II, but these appear to share no similarity in sequence or structure.

Structure

This riboswitch is composed of a single stem-loop. In some species there are large insertions of up to 210 nucleotides within this structure.

References

  1. Fuchs RT, Grundy FJ, Henkin TM (2006). "The S(MK) box is a new SAM-binding RNA for translational regulation of SAM synthetase". Nat. Struct. Mol. Biol. 13 (3): 226–33. doi:10.1038/nsmb1059. PMID 16491091.
  2. Fuchs RT, Grundy FJ, Henkin TM (2007). "S-adenosylmethionine directly inhibits binding of 30S ribosomal subunits to the SMK box translational riboswitch RNA". Proc. Natl. Acad. Sci. U.S.A. 104 (12): 4876–80. doi:10.1073/pnas.0609956104. PMID 17360376.

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