Download MendeleyStructure of the Guanidine III Riboswitch.
Huang, L., Wang, J., Wilson, T.J., Lilley, D.M.J.(2017) Cell Chem Biol 24: 1407-1415.e2
- PubMed: 28988949
- DOI: https://doi.org/10.1016/j.chembiol.2017.08.021
- Primary Citation of Related Structures:
5NWQ, 5NY8, 5NZ3, 5NZ6, 5NZD, 5O62, 5O69 - PubMed Abstract:
Riboswitches are structural elements found in mRNA molecules that couple small-molecule binding to regulation of gene expression, usually by controlling transcription or translation. We have determined high-resolution crystal structures of the ykkC guanidine III riboswitch from Thermobifida fusca. The riboswitch forms a classic H-type pseudoknot that includes a triple helix that is continuous with a central core of conserved nucleotides. These form a left-handed helical ramp of inter-nucleotide interactions, generating the guanidinium cation binding site. The ligand is hydrogen bonded to the Hoogsteen edges of two guanine bases. The binding pocket has a side opening that can accommodate a small side chain, shown by structures with bound methylguanidine, aminoguanidine, ethylguanidine, and agmatine. Comparison of the new structure with those of the guanidine I and II riboswitches reveals that evolution generated three different structural solutions for guanidine binding and subsequent gene regulation, although with some common elements.
Organizational Affiliation:
Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dow Street, Dundee DD1 5EH, UK.
