View source for 5kh8


==Solution structures of the apo state fluoride riboswitch==
<StructureSection load='5kh8' size='340' side='right'caption='[[5kh8]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5kh8]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Synthetic_construct Synthetic construct]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5KH8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5KH8 FirstGlance]. <br>
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=5kh8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5kh8 OCA], [https://pdbe.org/5kh8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5kh8 RCSB], [https://www.ebi.ac.uk/pdbsum/5kh8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5kh8 ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Riboswitches control gene expression through ligand-dependent structural rearrangements of the sensing aptamer domain. However, we found that the Bacillus cereus fluoride riboswitch aptamer adopts identical tertiary structures in solution with and without ligand. Using chemical-exchange saturation transfer (CEST) NMR spectroscopy, we revealed that the structured ligand-free aptamer transiently accesses a low-populated ( approximately 1%) and short-lived ( approximately 3 ms) excited conformational state that unravels a conserved 'linchpin' base pair to signal transcription termination. Upon fluoride binding, this highly localized, fleeting process is allosterically suppressed, which activates transcription. We demonstrated that this mechanism confers effective fluoride-dependent gene activation over a wide range of transcription rates, which is essential for robust toxicity responses across diverse cellular conditions. These results unveil a novel switching mechanism that employs ligand-dependent suppression of an aptamer excited state to coordinate regulatory conformational transitions rather than adopting distinct aptamer ground-state tertiary architectures, exemplifying a new mode of ligand-dependent RNA regulation.

An excited state underlies gene regulation of a transcriptional riboswitch.,Zhao B, Guffy SL, Williams B, Zhang Q Nat Chem Biol. 2017 Jul 17. doi: 10.1038/nchembio.2427. PMID:28719589<ref>PMID:28719589</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5kh8" style="background-color:#fffaf0;"></div>

==See Also==
*[[Riboswitch 3D structures|Riboswitch 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Synthetic construct]]
[[Category: Zhang Q]]
[[Category: Zhao B]]