title: Cocrystal structure of a class I preQ1 riboswitch reveals a pseudoknot recognizing an essential hypermodified nucleobase.
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.
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Klein
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Edwards
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Ferré-D'Amaré
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009704:Nucleoside Q / Q000031:analogs & derivatives* / Q000378:metabolism; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D012329:RNA, Bacterial; D012333:RNA, Messenger; D009704:Nucleoside Q; C021610:7-aminomethyl-7-deazaguanosine