Structural insights into ligand binding and gene expression control by an adenosylcobalamin riboswitch

Nat Struct Mol Biol. 2012 Nov;19(11):1182-4. doi: 10.1038/nsmb.2405. Epub 2012 Oct 14.


Coenzyme B(12) has a key role in various enzymatic reactions and controls expression of bacterial genes through riboswitches. Here we report the crystal structure of the Symbiobacterium thermophilum B(12) riboswitch bound to its ligand adenosylcobalamin. The riboswitch forms a unique junctional structure with a large ligand-binding pocket tailored for specific recognition of the adenosyl moiety and flanked by structural elements that stabilize the regulatory region and enable control of gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Pairing
  • Chromatography, Ion Exchange
  • Cobamides / chemistry*
  • Cobamides / metabolism
  • Crystallization
  • Electrophoresis, Polyacrylamide Gel
  • Gene Expression Regulation, Bacterial / genetics*
  • Gene Expression Regulation, Bacterial / physiology
  • Lactobacillales / enzymology*
  • Ligands
  • Models, Molecular*
  • Protein Conformation*
  • Riboswitch / genetics*
  • Riboswitch / physiology


  • Cobamides
  • Ligands
  • Riboswitch
  • cobamamide

Associated data

  • PDB/4GXY