Abstract
Significant advances in our understanding of RNA architecture, folding and recognition have emerged from structure–function studies on riboswitches, non-coding RNAs whose sensing domains bind small ligands and whose adjacent expression platforms contain RNA elements involved in the control of gene regulation. We now report on the ligand-bound structure of the Thermotoga petrophila fluoride riboswitch, which adopts a higher-order RNA architecture stabilized by pseudoknot and long-range reversed Watson–Crick and Hoogsteen A•U pair formation. The bound fluoride ion is encapsulated within the junctional architecture, anchored in place through direct coordination to three Mg2+ ions, which in turn are octahedrally coordinated to water molecules and five inwardly pointing backbone phosphates. Our structure of the fluoride riboswitch in the bound state shows how RNA can form a binding pocket selective for fluoride, while discriminating against larger halide ions. The T. petrophila fluoride riboswitch probably functions in gene regulation through a transcription termination mechanism.
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Protein Data Bank
Data deposits
Atomic coordinates of the structure of the fluoride riboswitch in the bound state have been deposited in the RCSB Protein Data Bank under the accession code 4ENC for the native structure and 4ENB for the Ir(NH3)63+-containing structure of the fluoride-bound riboswitch, as well as 3VRS, 4ENA and 4EN5 for crystals of the complex soaked in Mn2+-, Cs+- and Tl+-containing solutions.
References
Mironov, A. S. et al. Sensing small molecules by nascent RNA: a mechanism to control transcription in bacteria. Cell 111, 747–756 (2002)
Winkler, W., Nahvi, A. & Breaker, R. R. Thiamine derivatives bind messenger RNAs directly to regulate bacterial gene expression. Nature 419, 952–956 (2002)
Nudler, E. & Mironov, A. S. The riboswitch control of bacterial metabolism. Trends Biochem. Sci. 29, 11–17 (2004)
Winkler, W. C. & Breaker, R. R. Regulation of bacterial gene expression by riboswitches. Annu. Rev. Microbiol. 59, 487–517 (2005)
Serganov, A. & Patel, D. J. Ribozymes, riboswitches and beyond: regulation of gene expression without proteins. Nature Rev. Genet. 8, 776–790 (2007)
Montange, R. K. & Batey, R. T. Riboswitches: emerging themes in RNA structure and function. Annu. Rev. Biophys. 37, 117–133 (2008)
Serganov, A. et al. Structural basis for gene regulation by a thiamine pyrophosphate-sensing riboswitch. Nature 441, 1167–1171 (2006)
Thore, S., Leinungdut, M. & Ban, N. Structure of the eukaryotic thiamine pyrophosphate riboswitch with its regulatory ligand. Science 312, 1208–1211 (2006)
Lang, K., Rieder, R. & Micura, R. Ligand-induced folding of the thiM TPP riboswitch investigated by a structure-based fluorescence spectroscopic approach. Nucleic Acids Res. 35, 5370–5378 (2007)
Anthony, P. C., Perez, C. F., Garcia-Garcia, C. & Block, S. M. Folding energy landscape of the thiamine pyrophosphate riboswitch aptamer. Proc. Natl Acad. Sci. USA 109, 1485–1489 (2012)
Mironov, A. S. et al. Sensing small molecules by nascent RNA: a mechanism to control transcription in bacteria. Cell 111, 747–756 (2002)
Serganov, A., Huang, L. & Patel, D. J. Coenzyme recognition and gene regulation by a flavin mononucleotide riboswitch. Nature 458, 233–237 (2009)
Baker, J. L. et al. Widespread genetic switches and toxicity resistance proteins for fluoride. Science 335, 233–235 (2012)
Mandal, M. et al. Riboswitches control fundamental biochemical pathways in Bacillus subtilis and other bacteria. Cell 113, 577–586 (2003)
Batey, R. T., Gilbert, S. D. & Montange, R. K. Structure of a natural guanine-responsive riboswitch complexed with the metabolite hypoxanthine. Nature 432, 411–415 (2004)
Serganov, A. et al. Structural basis for discriminative regulation of gene expression by adenine- and guanine-sensing mRNAs. Chem. Biol. 11, 1729–1741 (2004)
Mandal, M. et al. A glycine-dependent riboswitch that uses cooperative binding to control gene expression. Science 306, 275–279 (2004)
Huang, L., Serganov, A. & Patel, D. J. Structural insights into ligand recognition by a sensing domain of the cooperative glycine riboswitch. Mol. Cell 40, 774–786 (2010)
Butler, E. B., Xiong, Y., Wang, J. & Strobel, S. A. Structural basis of cooperative ligand binding by the glycine riboswitch. Chem. Biol. 18, 293–298 (2011)
Heikinheimo, P. et al. Toward a quantum-mechanical description of metal-assisted phosphoryl transfer in pyrophosphatase. Proc. Natl Acad. Sci. USA 98, 3121–3126 (2001)
Auffinger, P., Hays, F. H., Westhof, E. & Ho, P. S. Halogen bonds in biological molecules. Proc. Natl Acad. Sci. USA 101, 16789–16794 (2004)
Hanna, R. & Doudna, J. A. Metal ions in ribozyme folding and catalysis. Curr. Opin. Chem. Biol. 4, 166–170 (2000)
Correll, C. C., Freeborn, B., Moore, P. B. & Steitz, T. A. Metals, motifs and recognition in the crystal structure of a 5S RNA domain. Cell 91, 705–712 (1997)
Cate, J. H., Hanna, R. L. & Doudna, J. A. A magnesium ion core at the heart of a ribozyme domain. Nature Struct. Biol. 4, 553–558 (1997)
Cromie, M. J., Shi, Y., Latifi, T. & Groisman, E. A. An RNA sensor for intracellular Mg2+. Cell 125, 71–84 (2006)
Dann, C. E., III et al. Structure and mechanism of a metal-sensing regulatory RNA. Cell 130, 878–892 (2007)
Pikovskaya, O. et al. Preparation and crystallization of riboswitch-ligand complexes. Methods Mol. Biol. 540, 115–128 (2009)
Pape, T. & Schneider, T. R. HKL2MAP: a graphical user interface for phasing with SHELX programs. J. Appl. Cryst. 37, 843–844 (2004)
Adams, P. D. et al. PHENIX: building new software for automated crystallographic structure determination. Acta Crystallogr. D 58, 1948–1954 (2002)
Emsley, P. & Cowtan, K. Coot: model-building tools for molecular graphics. Acta Crystallogr. D 60, 2126–2132 (2004)
Murshudov, G. N., Vagin, A. A. & Dodson, E. J. Refinement of macromolecular structures by the maximum-likelihood method. Acta Crystallogr. D 53, 240–255 (1997)
Feig, A. L. & Uhlenbeck, O. C. in The RNA World 2nd edn (eds Gesteland, R. F., Cech, T. R. & Atkins, J. F. ) 287–319 (Cold Spring Harbor Laboratory Press, 1999)
Acknowledgements
We thank J. Goldberg and C. Lima for discussion and insights, Y. Liu for recording imino proton NMR spectra, and the personnel of the synchrotron beamlines 24-ID-C/E at the Advanced Photon Source, Argonne National Laboratory for their assistance. This research was funded by NIH grant GM34504 to D.J.P.
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A.R. generated and purified RNA constructs, grew diffraction quality crystals, collected synchrotron data sets and solved the structure of the fluoride riboswitch in the bound state under the supervision of D.J.P.; K.R.R. assisted in crystallographic aspects of the structure determination, including finding unique solutions to the positioning of the Mg and fluoride ions. D.J.P. wrote the manuscript with the assistance of the other authors, all of whom discussed the results and commented on the manuscript.
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Ren, A., Rajashankar, K. & Patel, D. Fluoride ion encapsulation by Mg2+ ions and phosphates in a fluoride riboswitch. Nature 486, 85–89 (2012). https://doi.org/10.1038/nature11152
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DOI: https://doi.org/10.1038/nature11152
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