6HAG
The structure of the SAM/SAH-binding riboswitch.
Summary for 6HAG
| Entry DOI | 10.2210/pdb6hag/pdb |
| NMR Information | BMRB: 27452 |
| Descriptor | SAM Riboswitch, S-ADENOSYL-L-HOMOCYSTEINE (2 entities in total) |
| Functional Keywords | riboswitch, sam, sah, pseudoknot, rna |
| Biological source | Proteobacteria |
| Total number of polymer chains | 1 |
| Total formula weight | 14217.64 |
| Authors | Weickhmann, A.K. (deposition date: 2018-08-07, release date: 2019-01-09, Last modification date: 2025-12-10) |
| Primary citation | Weickhmann, A.K.,Keller, H.,Wurm, J.P.,Strebitzer, E.,Juen, M.A.,Kremser, J.,Weinberg, Z.,Kreutz, C.,Duchardt-Ferner, E.,Wohnert, J. The structure of the SAM/SAH-binding riboswitch. Nucleic Acids Res., 47:2654-2665, 2019 Cited by PubMed Abstract: S-adenosylmethionine (SAM) is a central metabolite since it is used as a methyl group donor in many different biochemical reactions. Many bacteria control intracellular SAM concentrations using riboswitch-based mechanisms. A number of structurally different riboswitch families specifically bind to SAM and mainly regulate the transcription or the translation of SAM-biosynthetic enzymes. In addition, a highly specific riboswitch class recognizes S-adenosylhomocysteine (SAH)-the product of SAM-dependent methyl group transfer reactions-and regulates enzymes responsible for SAH hydrolysis. High-resolution structures are available for many of these riboswitch classes and illustrate how they discriminate between the two structurally similar ligands SAM and SAH. The so-called SAM/SAH riboswitch class binds both ligands with similar affinities and is structurally not yet characterized. Here, we present a high-resolution nuclear magnetic resonance structure of a member of the SAM/SAH-riboswitch class in complex with SAH. Ligand binding induces pseudoknot formation and sequestration of the ribosome binding site. Thus, the SAM/SAH-riboswitches are translational 'OFF'-switches. Our results establish a structural basis for the unusual bispecificity of this riboswitch class. In conjunction with genomic data our structure suggests that the SAM/SAH-riboswitches might be an evolutionary late invention and not a remnant of a primordial RNA-world as suggested for other riboswitches. PubMed: 30590743DOI: 10.1093/nar/gky1283 PDB entries with the same primary citation |
| Experimental method | SOLUTION NMR |
Structure validation
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