Cocrystal structure of a class I preQ1 riboswitch reveals a pseudoknot recognizing an essential hypermodified nucleobase
Klein, D.J., Edwards, T.E., Ferre-D'Amare, A.R.(2009) Nat Struct Mol Biol 16: 343-344
- PubMed: 19234468 
- DOI: https://doi.org/10.1038/nsmb.1563
- Primary Citation of Related Structures:  
3FU2, 3K1V - PubMed Abstract: 
Riboswitches are mRNA domains that bind metabolites and modulate gene expression in cis. We report cocrystal structures of a remarkably compact riboswitch (34 nucleotides suffice for ligand recognition) from Bacillus subtilis that is selective for the essential nucleobase preQ(1) (7-aminomethyl-7-deazaguanine). The structures reveal a previously unrecognized pseudoknot fold and suggest a conserved gene-regulatory mechanism whereby ligand binding promotes sequestration of an RNA segment that otherwise assembles into a transcriptional antiterminator.
Organizational Affiliation: 
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA.