title: Riboswitches that sense S-adenosylhomocysteine and activate genes involved in coenzyme recycling.
abstract: We have identified a highly conserved RNA motif that occurs upstream of genes involved in S-adenosyl-L-methionine (SAM) recycling in many Gram-positive and Gram-negative species of bacteria. The phylogenetic distribution and the conserved structural features of representatives of this motif are indicative of riboswitch function. Riboswitches are widespread metabolite-sensing gene control elements that are typically found in the 5' untranslated regions (UTRs) of bacterial mRNAs. We experimentally verified that examples of this RNA motif specifically recognize S-adenosylhomocysteine (SAH) in protein-free in vitro assays, and confirmed that these RNAs strongly discriminate against SAM and other closely related analogs. A representative SAH motif was found to activate expression of a downstream gene in vivo when the metabolite is bound. These observations confirm that SAH motif RNAs are distinct ligand-binding aptamers for a riboswitch class that selectively binds SAH and controls genes essential for recycling expended SAM coenzymes.
authors: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
authors: Joy Xin
authors: JX
authors: Wang
authors: Elaine R
authors: ER
authors: Lee
authors: Dianali Rivera
authors: DR
authors: Morales
authors: Jinsoo
authors: J
authors: Lim
authors: Ronald R
authors: RR
authors: Breaker
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D003067:Coenzymes / Q000378:metabolism*; D017124:Conserved Sequence; D005786:Gene Expression Regulation; D006710:Homocysteine / Q000378:metabolism; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry / Q000235:genetics*; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012435:S-Adenosylhomocysteine / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D003067:Coenzymes; D012329:RNA, Bacterial; D006710:Homocysteine; D012313:RNA; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D008715:Methionine