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Cited by 29RNA and protein synthesis mechanismsEnzyme Structure and FunctionProtein Structure and Dynamics

Deflating the RNA Mg 2+ bubble: stereochemistry to the rescue!

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Auffinger, Pascal, Ennifar, Eric, D'Ascenzo, Luigi·2021·RNA
DOI 10.1261/rna.076067.120PMC PMC7901845

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Abstract

Proper evaluation of the ionic structure of biomolecular systems through X-ray and cryo-EM techniques remains challenging but is essential for advancing our understanding of the underlying structure/activity/solvent relationships. However, numerous studies overestimate the number of Mg 2+ in deposited structures due to assignment errors finding their origin in improper consideration of stereochemical rules. Herein, to tackle such issues, we reevaluate the PDBid 6QNR and 6SJ6 models of the ribosome ionic structure. We establish that stereochemical principles need to be carefully pondered when examining ion binding features, even when K + anomalous signals are available as is the case for the 6QNR PDB entry. For ribosomes, assignment errors can result in misleading conceptions of their solvent structure. For instance, present stereochemical analysis results in a significant decrease of the number of assigned Mg 2+ in 6QNR, suggesting that K + and not Mg 2+ is the prevalent ion in the ribosome first solvation shell. We stress that the use of proper stereochemical guidelines in combination or not with other identification techniques, such as those pertaining to the detection of transition metals, of some anions and of K + anomalous signals, is critical for deflating the current Mg 2+ bubble witnessed in many ribosome and other RNA structures. We also stress that for the identification of lighter ions such as Mg 2+ , Na + , …, for which no anomalous signals can be detected, stereochemistry coupled with high resolution structures (<2.4 Å) remains the best currently available option.

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  • A subset of ribosomally associated K+ is thought to be localized deep within the macromolecular structure where residence times may approach the lifetime of the folded ribosomal subunits.

    “A subset of ribosomally associated K+ is thought to be localized deep within the macromolecular structure where residence times may approach the lifetime of the folded ribosomal subunits.54”

    From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [54]

    The paper’s Abstract makes the contrary distinction: it describes K+ as weakly coordinating and says that Mg2+ bound in the rRNA core may have residence times approaching the lifetime of folded ribosomal subunits. It does not assign that long residence time to K+. No page number is available in our copy. (LLM, conf=0.90)

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  • >3000 cation-binding sites were visualized in the Thermus thermophilus 70S ribosome and assigned as Mg2+, but those assignments have been challenged on experimental and stereochemical grounds.

    “As an upper limit, > 3000 cation-binding sites were visualized in the Thermus thermophilus 70S ribosome51 and assigned as Mg2+, but those assignments have been challenged on both experimental52 and stereochemical54 grounds.”

    From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [54]

  • With ∼3 × 10^4 ribosomes per fL of cell volume and up to ∼400 K+ site-specifically bound per ribosome, ribosomes may bind up to ∼1.2 × 10^7 K+ ions (∼10% of the cell quota) in these sites alone.

    “With ∼3 × 104 ribosomes per fL (10–15 liters) of cell volume,56 and up to ∼400 K+ site-specifically bound per ribosome,54 ribosomes may bind up to ∼1.2 × 107 K+ ions (∼10% of the cell quota) in these sites alone.”

    From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [54]

  • Stereochemical considerations argue that many sites assigned as Mg2+ in ribosome structures may be occupied instead by K+.

    “Stereochemical considerations argue that many sites assigned as Mg2+ (Figure 4c) may be occupied instead by K+ (Figure 4d).52,54”

    From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [54]

  • Further analysis using stereochemical constraints refined these estimates and assigned ~400 monovalent ions and ~100 Mg2+ in the first solvation shell.

    “Further analysis using stereochemical constraints refined these estimates further and assigned ∼400 monovalent ions and ∼100 Mg2+ in the first solvation shell.54”

    From Metals in Motion: Understanding Labile Metal Pools in Bacteria (2025) · cites this paper as [54]

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Research works printed but not linked: 64

  1. Auffinger P, Bielecki L, Westhof E. 2003 The Mg2+ binding sites of the 5S rRNA loop E motif as investigated by molecular dynamics simulations. Chem Biol 10: 551– 561. 10.1016/S1074-5521(03)00121-2 12837388 · DOI
  2. Auffinger P, Bielecki L, Westhof E. 2004a Anion binding to nucleic acids. Structure 12: 379– 388. 10.1016/j.str.2004.02.015 15016354 · DOI
  3. Auffinger P, Bielecki L, Westhof E. 2004b Symmetric K+ and Mg2+ ion-binding sites in the 5S rRNA loop E inferred from molecular dynamics simulations. J Mol Biol 335: 555– 571. 10.1016/j.jmb.2003.10.057 14672663 · DOI
  4. Auffinger P, D'Ascenzo L, Ennifar E. 2016 Sodium and potassium interactions with nucleic acids. Met Ions Life Sci 16: 167– 201. 10.1007/978-3-319-21756-7_6 26860302 · DOI
  5. Ball P, Hallsworth JE. 2015 Water structure and chaotropicity: their uses, abuses and biological implications. Phys Chem Chem Phys 17: 8297– 8305. 10.1039/C4CP04564E 25628033 · DOI
  6. Basu S, Olieric V, Leonarski F, Matsugaki N, Kawano Y, Takashi T, Huang CY, Yamada Y, Vera L, Olieric N, 2019 Long-wavelength native-SAD phasing: opportunities and challenges. IUCrJ 6: 373– 386. 10.1107/S2052252519002756 PMC6503925 31098019 · DOI
  7. Bleuzen A, Pittet PA, Helm L, Merbach AE. 1997 Water exchange on magnesium(II) in aqueous solution: a variable temperature and pressure 17O NMR study. Magn Reson Chem 35: 765– 773. 10.1002/(SICI)1097-458X(199711)35:11<765::AID-OMR169>3.0.CO;2-F · DOI
  8. Bowman JC, Lenz TK, Hud NV, Williams LD. 2012 Cations in charge: magnesium ions in RNA folding and catalysis. Curr Opin Struct Biol 22: 262– 272. 10.1016/j.sbi.2012.04.006 22595008 · DOI
  9. Bowman JC, Petrov AS, Williams LD. 2018 Role of cations in RNA folding and function. In Handbook of astrobiology (ed. Kolb VM), pp. 421– 435. CRC Press, Boca Raton, FL.
  10. Brzezinski D, Dauter Z, Minor W, Jaskolski M. 2020 On the evolution of the quality of macromolecular models in the PDB. FEBS J 287: 2685– 2698. 10.1111/febs.15314 32311227 PMC7340579 · DOI
  11. Danchin A, Nikel PI. 2019 Why nature chose potassium. J Mol Evol 87: 271– 288. 10.1007/s00239-019-09915-2 31659374 · DOI · Paper page
  12. Dasarathy S, Mookerjee RP, Rackayova V, Rangroo Thrane V, Vairappan B, Ott P, Rose CF. 2017 Ammonia toxicity: from head to toe? Metab Brain Dis 32: 529– 538. 10.1007/s11011-016-9938-3 28012068 PMC8839071 · DOI
  13. D'Ascenzo L, Auffinger P. 2016 Anions in nucleic acid crystallography. Methods Mol Biol 1320: 337– 351. 10.1007/978-1-4939-2763-0_22 26227054 · DOI
  14. Dauter Z, Wlodawer A, Minor W, Jaskolski M, Rupp B. 2014 Avoidable errors in deposited macromolecular structures: an impediment to efficient data mining. IUCrJ 1: 179– 193. 10.1107/S2052252514005442 PMC4086436 25075337 · DOI
  15. Emsley P, Lohkamp B, Scott WG, Cowtan K. 2010 Features and development of Coot. Acta Crystallogr D Biol Crystallogr 66: 486– 501. 10.1107/S0907444910007493 20383002 PMC2852313 · DOI
  16. Ennifar E, Walter P, Dumas P. 2003 A crystallographic study of the binding of 13 metal ions to two related RNA duplexes. Nucleic Acids Res 31: 2671– 2682. 10.1093/nar/gkg350 12736317 PMC156032 · DOI
  17. Epstein W. 2003 The roles and regulation of potassium in bacteria. Prog Nucleic Acid Res Mol Biol 75: 293– 320. 10.1016/S0079-6603(03)75008-9 14604015 · DOI
  18. Fan Y, Gaffney BL, Jones RA. 2005 RNA GG·UU motif binds K+ but not Mg2+. J Am Chem Soc 127: 17588– 17589. 10.1021/ja0555522 16351072 · DOI
  19. Gabdulkhakov A, Nikonov S, Garber M. 2013 Revisiting the Haloarcula marismortui 50S ribosomal subunit model. Acta Crystallogr D Biol Crystallogr 69: 997– 1004. 10.1107/S0907444913004745 23695244 · DOI
  20. Grime GW, Zeldin OB, Snell ME, Lowe ED, Hunt JF, Montelione GT, Tong L, Snell EH, Garman EF. 2020 High-throughput PIXE as an essential quantitative assay for accurate metalloprotein structural analysis: development and application. J Am Chem Soc 142: 185– 197. 10.1021/jacs.9b09186 31794207 · DOI
  21. Groom CR, Bruno IJ, Lightfoot MP, Ward SC. 2016 The Cambridge structural database. Acta Crystallogr D Biol Crystallogr 72: 171– 179. 10.1107/S205327331501877X PMC4822653 27048719 · DOI
  22. Handing KB, Niedzialkowska E, Shabalin IG, Kuhn ML, Zheng H, Minor W. 2018 Characterizing metal-binding sites in proteins with X-ray crystallography. Nat Protoc 13: 1062– 1090. 10.1038/nprot.2018.018 29674755 PMC6235626 · DOI
  23. Harding MJ, Nowicki MW, Walkinshaw MD. 2010 Metals in protein structures: a review of their principal features. Cryst Rev 16: 247– 302. 10.1080/0889311X.2010.485616 · DOI
  24. Hsiao C, Williams LD. 2009 A recurrent magnesium-binding motif provides a framework for the ribosomal peptidyl transferase center. Nucleic Acids Res 37: 3134– 3142. 10.1093/nar/gkp119 19279186 PMC2691814 · DOI
  25. Hsiao C, Tannenbaum E, VanDeusen H, Hershkovitz E, Perng G, Tannenbaum AR, Williams LD. 2009 Complexes of nucleic acids with group I and II cations. In Nucleic acid-metal ion interactions (ed. Hud NV), pp. 1– 38. Royal Society of Chemistry, Cambridge.
  26. Jenner LB, Demeshkina N, Yusupova G, Yusupov M. 2010 Structural aspects of messenger RNA reading frame maintenance by the ribosome. Nat Struct Mol Biol 17: 555– 560. 10.1038/nsmb.1790 20400952 · DOI · Paper page
  27. Joung IS, Cheatham TE III. 2009 Molecular dynamics simulations of the dynamic and energetic properties of alkali and halide ions using water-model-specific ion parameters. J Phys Chem B 113: 13279– 13290. 10.1021/jp902584c 19757835 PMC2755304 · DOI
  28. Khusainov I, Fatkhullin B, Pellegrino S, Bikmullin A, Liu WT, Gabdulkhakov A, Shebel AA, Golubev A, Zeyer D, Trachtmann N, 2020 Mechanism of ribosome shutdown by RsfS in Staphylococcus aureus revealed by integrative structural biology approach. Nat Commun 11: 1656 10.1038/s41467-020-15517-0 32245971 PMC7125091 · DOI
  29. Klein DJ, Moore PB, Steitz TA. 2004 The contribution of metal ions to the structural stability of the large ribosomal subunit. RNA 10: 1366– 1379. 10.1261/rna.7390804 15317974 PMC1370624 · DOI
  30. Kowiel M, Brzezinski D, Porebski PJ, Shabalin IG, Jaskolski M, Minor W. 2018 Automatic recognition of ligands in electron density by machine learning. Bioinformatics 35: 452– 461. 10.1093/bioinformatics/bty626 PMC6361236 30016407 · DOI
  31. Kruse H, Sponer J, Auffinger P. 2019 Comment on “Evaluating unexpectedly short non-covalent distances in X-ray crystal structures of proteins with electronic structure analysis.” J Chem Inf Model 59: 3605– 3608. 10.1021/acs.jcim.9b00473 31424937 · DOI
  32. Lange J, Vriend G. 2020 Citius, Altius, Fortius. Proteins 2020: 1– 7. 10.1002/prot.12345. 32530545 · DOI
  33. Leonarski F, D'Ascenzo L, Auffinger P. 2017 Mg2+ ions: do they bind to nucleobase nitrogens? Nucleic Acids Res 45: 987– 1004. 10.1093/nar/gkw1175 27923930 PMC5314772 · DOI
  34. Leonarski F, D'Ascenzo L, Auffinger P. 2019 Nucleobase carbonyl groups are poor Mg2+ inner-sphere binders but excellent monovalent ion binders: a critical PDB survey. RNA 25: 173– 192. 10.1261/rna.068437.118 30409785 PMC6348993 · DOI · Paper page
  35. Liebschner D, Yamada Y, Matsugaki N, Senda M, Senda T. 2016 On the influence of crystal size and wavelength on native SAD phasing. Acta Crystallogr D Biol Crystallogr 72: 728– 741. 10.1107/S2059798316005349 27303793 · DOI
  36. Liebschner D, Afonine PV, Baker ML, Bunkoczi G, Chen VB, Croll TI, Hintze B, Hung LW, Jain S, McCoy AJ, 2019 Macromolecular structure determination using X-rays, neutrons and electrons: recent developments in Phenix. Acta Crystallogr D Biol Crystallogr 75: 861– 877. 10.1107/S2059798319011471 PMC6778852 31588918 · DOI
  37. Liu Q, Hendrickson WA. 2017 Contemporary use of anomalous diffraction in biomolecular structure analysis. Methods Mol Biol 1607: 377– 399. 10.1007/978-1-4939-7000-1_16 28573582 PMC5541782 · DOI
  38. Liu Q, Liu Q, Hendrickson WA. 2013 Robust structural analysis of native biological macromolecules from multi-crystal anomalous diffraction data. Acta Crystallogr D Biol Crystallogr 69: 1314– 1332. 10.1107/S0907444913001479 23793158 PMC3689535 · DOI
  39. Miller-Fleming L, Olin-Sandoval V, Campbell K, Ralser M. 2015 Remaining mysteries of molecular biology: the role of polyamines in the cell. J Mol Biol 427: 3389– 3406. 10.1016/j.jmb.2015.06.020 26156863 · DOI · Paper page
  40. Minor W, Dauter Z, Helliwell JR, Jaskolski M, Wlodawer A. 2016 Safeguarding structural data repositories against bad apples. Structure 24: 216– 220. 10.1016/j.str.2015.12.010 26840827 PMC4743038 · DOI
  41. Nierhaus KH. 2014 Mg2+, K+, and the ribosome. J Bacteriol 196: 3817– 3819. 10.1128/JB.02297-14 25225274 PMC4248827 · DOI · Paper page
  42. Noeske J, Wasserman MR, Terry DS, Altman RB, Blanchard SC, Cate JH. 2015 High-resolution structure of the Escherichia coli ribosome. Nat Struct Mol Biol 22: 336– 341. 10.1038/nsmb.2994 25775265 PMC4429131 · DOI
  43. Olieric V, Weinert T, Finke AD, Anders C, Li D, Olieric N, Borca CN, Steinmetz MO, Caffrey M, Jinek M, 2016 Data-collection strategy for challenging native SAD phasing. Acta Crystallogr D Biol Crystallogr 72: 421– 429. 10.1107/S2059798315024110 PMC4784673 26960129 · DOI
  44. Panjikar S, Thomsen L, O'Donnell KM, Riboldi-Tunnicliffe A. 2015 A step towards long-wavelength protein crystallography: subjecting protein crystals to a vacuum. J Appl Cryst 48: 913– 916. 10.1107/S1600576715006147 26089765 PMC4453978 · DOI
  45. Pettersen EF, Goddard TD, Huang CC, Couch GS, Greenblatt DM, Meng EC, Ferrin TE. 2004 UCSF Chimera–a visualization system for exploratory research and analysis. J Comput Chem 25: 1605– 1612. 10.1002/jcc.20084 15264254 · DOI
  46. Qi HW, Kulik HJ. 2019 Evaluating unexpectedly short non-covalent distances in X-ray crystal structures of proteins with electronic structure analysis. J Chem Inf Model 59: 2199– 2211. 10.1021/acs.jcim.9b00144 30875210 · DOI
  47. Rozov A, Demeshkina N, Khusainov I, Westhof E, Yusupov M, Yusupova G. 2016 Novel base-pairing interactions at the tRNA wobble position crucial for accurate reading of the genetic code. Nat Commun 7: 10457 10.1038/ncomms10457 26791911 PMC4736104 · DOI
  48. Rozov A, Khusainov I, El Omari K, Duman R, Mykhaylyk V, Yusupov M, Westhof E, Wagner A, Yusupova G. 2019 Importance of potassium ions for ribosome structure and function revealed by long-wavelength X-ray diffraction. Nat Commun 10: 2519 10.1038/s41467-019-10409-4 31175275 PMC6555806 · DOI · Paper page
  49. Rupp B, Wlodawer A, Minor W, Helliwell JR, Jaskolski M. 2016 Correcting the record of structural publications requires joint effort of the community. FEBS J 283: 4452– 4457. 10.1111/febs.13765 27229767 PMC5124416 · DOI
  50. Shabalin IG, Porebski PJ, Minor W. 2018 Refining the macromolecular model: achieving the best agreement with the data from X-ray diffraction experiment. Crystallogr Rev 24: 236– 262. 10.1080/0889311X.2018.1521805 30416256 PMC6219471 · DOI
  51. Taylor R, Wood PA. 2019 A million crystal structures: the whole is greater than the sum of its parts. Chem Rev 119: 9427– 9477. 10.1021/acs.chemrev.9b00155 31244003 · DOI
  52. Tereshko V, Wilds CJ, Minasov G, Prakash TP, Maier MA, Howard A, Wawrzak Z, Manoharan M, Egli M. 2001 Detection of alkali metal ions in DNA crystals using state-of-the-art X-ray diffraction experiments. Nucleic Acids Res 29: 1208– 1215. 10.1093/nar/29.5.1208 11222771 PMC29719 · DOI
  53. Wagner A, Duman R, Henderson K, Mykhaylyk V. 2016 In-vacuum long-wavelength macromolecular crystallography. Acta Crystallogr D Biol Crystallogr 72: 430– 439. 10.1107/S2059798316001078 PMC4784674 26960130 · DOI
  54. Wagner A, Duman R, Omari K, Grama V, Mykhaylykh V. 2018 The long-wavelength macromolecular crystallography I23 at Diamond light source. Nihon Kessho Gakkaishi 60: 233– 239. 10.5940/jcrsj.60.233 · DOI
  55. Wang W, Zhao J, Han Q, Wang G, Yang G, Shallop AJ, Liu J, Gaffney BL, Jones RA. 2009 Modulation of RNA metal binding by flanking bases: 15N NMR evaluation of GC, tandem GU, and tandem GA sites. Nucleosides Nucleotides Nucleic Acids 28: 424– 434. 10.1080/15257770903044234 20183593 PMC2829742 · DOI
  56. Westhof E, Yusupov M, Yusupova G. 2019 The multiple flavors of GoU pairs in RNA. J Mol Recognit 32: e2782 10.1002/jmr.2782 31033092 PMC6617799 · DOI
  57. Williams LD. 2005 Between objectivity and whim: nucleic acid structural biology. Top Curr Chem 253: 77– 88. 10.1007/b100443 · DOI
  58. Wlodawer A. 2017 Stereochemistry and validation of macromolecular structures. Methods Mol Biol 1607: 595– 610. 10.1007/978-1-4939-7000-1_24 28573590 PMC5560084 · DOI
  59. Wlodawer A, Minor W, Dauter Z, Jaskolski M. 2013 Protein crystallography for aspiring crystallographers or how to avoid pitfalls and traps in macromolecular structure determination. FEBS J 280: 5705– 5736. 10.1111/febs.12495 24034303 PMC4080831 · DOI
  60. Wlodawer A, Dauter Z, Porebski PJ, Minor W, Stanfield R, Jaskolski M, Pozharski E, Weichenberger CX, Rupp B. 2018 Detect, correct, retract: how to manage incorrect structural models. FEBS J 285: 444– 466. 10.1111/febs.14320 29113027 PMC5799025 · DOI
  61. Zheng H, Chordia MD, Cooper DR, Chruszcz M, Muller P, Sheldrick GM, Minor W. 2014 Validation of metal-binding sites in macromolecular structures with the CheckMyMetal web server. Nat Protoc 9: 156– 170. 10.1038/nprot.2013.172 24356774 PMC4410975 · DOI
  62. Zheng H, Shabalin IG, Handing KB, Bujnicki JM, Minor W. 2015 Magnesium-binding architectures in RNA crystal structures: validation, binding preferences, classification and motif detection. Nucleic Acids Res 43: 3789– 3801. 10.1093/nar/gkv225 25800744 PMC4402538 · DOI · Paper page
  63. Zheng H, Cooper DR, Porebski PJ, Shabalin IG, Handing KB, Minor W. 2017 CheckMyMetal: a macromolecular metal-binding validation tool. Acta Crystallogr D Biol Crystallogr 73: 223– 233. 10.1107/S2059798317001061 PMC5349434 28291757 · DOI
  64. Zhou Y, Morais-Cabral JH, Kaufman A, MacKinnon R. 2001 Chemistry of ion coordination and hydration revealed by a K+ channel-Fab complex at 2.0 A resolution. Nature 414: 43– 48. 10.1038/35102009 11689936 · DOI

Cited by

Sorted by citations

Authors
Auffinger, P., Ennifar, E., & D'Ascenzo, L.
Affiliations
Centre National de la Recherche Scientifique (FR)
Corresponding author
Auffinger, Pascal
ORCID
Venue
RNA
Publisher
Cold Spring Harbor Laboratory
Published
2020-12-02
Volume
27
Issue
3
Pages
243-252
ISSN
  • 1355-8382 (ISSN-L)
  • 1469-9001
DOI
10.1261/rna.076067.120
PMC
PMC7901845
OpenAlex
W3107309388
Cited by
29
References
0
Citations by year
2026: 3 · 2025: 8 · 2024: 4 · 2023: 5 · 2022: 5 · 2021: 4
FWCI
1.12
Type
journal article
Language
en
Open access
Locations
  • RNA (publishedVersion)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by-nd)
  • PubMed Central (publishedVersion, cc-by-nc)
  • PubMed (publishedVersion)
  • HAL (submittedVersion, cc-by)
  • HAL (submittedVersion, cc-by-nc)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › RNA and protein synthesis mechanisms
  • Physical Sciences › Materials Science › Materials Chemistry › Enzyme Structure and Function
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Protein Structure and Dynamics
Keywords
magnesium binding, resonant scattering, potassium ions, first solvation shell

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