Cocrystal structure of a class I preQ1 riboswitch reveals a pseudoknot recognizing an essential hypermodified nucleobase.
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.
Klein
Daniel J
DJ
Division of Basic Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109-1024, USA.
Edwards
Thomas E
TE
Ferré-D'Amaré
Adrian R
AR
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*
D012329:RNA, Bacterial; D012333:RNA, Messenger; D009704:Nucleoside Q; C021610:7-aminomethyl-7-deazaguanosine