The aptamer core of SAM-IV riboswitches mimics the ligand-binding site of SAM-I riboswitches

RNA. 2008 May;14(5):822-8. doi: 10.1261/rna.988608. Epub 2008 Mar 27.


A novel family of riboswitches, called SAM-IV, is the fourth distinct set of mRNA elements to be reported that regulate gene expression via direct sensing of S-adenosylmethionine (SAM or AdoMet). SAM-IV riboswitches share conserved nucleotide positions with the previously described SAM-I riboswitches, despite rearranged structures and nucleotide positions with family-specific nucleotide identities. Sequence analysis and molecular recognition experiments suggest that SAM-I and SAM-IV riboswitches share similar ligand binding sites, but have different scaffolds. Our findings support the view that RNA has considerable structural versatility and reveal that riboswitches exploit this potential to expand the scope of RNA in genetic regulation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Aptamers, Nucleotide / chemistry
  • Aptamers, Nucleotide / genetics*
  • Aptamers, Nucleotide / metabolism*
  • Base Sequence
  • Binding Sites / genetics
  • DNA Primers / genetics
  • Evolution, Molecular
  • Ligands
  • Nucleic Acid Conformation
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / genetics
  • RNA, Bacterial / metabolism
  • RNA, Messenger / chemistry
  • RNA, Messenger / classification
  • RNA, Messenger / genetics*
  • RNA, Messenger / metabolism*
  • S-Adenosylmethionine / metabolism*
  • Streptomyces coelicolor / genetics
  • Streptomyces coelicolor / metabolism


  • Aptamers, Nucleotide
  • DNA Primers
  • Ligands
  • RNA, Bacterial
  • RNA, Messenger
  • S-Adenosylmethionine