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Structural studies of ligand binding by mRNA riboswitches
Author(s) -
Batey Robert T.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a41-c
Subject(s) - riboswitch , aptamer , ligand (biochemistry) , allosteric regulation , repressor , rna , chemistry , messenger rna , microbiology and biotechnology , untranslated region , computational biology , gene expression , regulation of gene expression , biology , gene , non coding rna , genetics , biochemistry , receptor
Riboswitches are highly structured elements within the 5′‐untranslated regions (UTRs) of messenger RNAs (mRNAs) that specifically bind small molecule metabolites to regulate gene expression in a cis‐fashion. This form riboregulation typically comprises two domains: an “aptamer domain” that specifically recognizes and binds a specific ligand and an “expression platform” that directs expression of the mRNA at the transcriptional or translational level based upon whether or not the aptamer domain is ligand‐bound. Our laboratory has solved the X‐ray crystal structures of the aptamer domains purine and S‐adenosylmethionine responsive riboswitches in complex with their cognate ligands, revealing complex tertiary architectures that scaffold the ligand‐binding pocket. In each case, almost all of the functional groups of the ligand are directly or indirectly read by the RNA, allowing for these are regulatory elements to achieve their extremely high metabolite specificity. Regulation is achieved through a series of ligand‐induced tertiary structural changes in the RNA that serve to stabilize a helix that forms part of a secondary structural switch with the expression platform. It is very likely that all bacterial riboswitches operate by this mechanism in which ligand‐induced allosteric changes in the RNA drive gene expression, very similar to that of protein repressors.