One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions
Inositol poly- and pyrophosphates (InsPs and PP-InsPs) are central eukaryotic messengers. These very highly phosphorylated molecules can exist in two distinct conformations, a canonical one with five phosphoryl groups in equatorial positions, and a “flipped” conformation with five axial substituents...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-04-01
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| Series: | Biomolecules |
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| Online Access: | https://www.mdpi.com/2218-273X/13/4/645 |
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| author | Leonie Kurz Peter Schmieder Nicolás Veiga Dorothea Fiedler |
| author_facet | Leonie Kurz Peter Schmieder Nicolás Veiga Dorothea Fiedler |
| author_sort | Leonie Kurz |
| collection | DOAJ |
| description | Inositol poly- and pyrophosphates (InsPs and PP-InsPs) are central eukaryotic messengers. These very highly phosphorylated molecules can exist in two distinct conformations, a canonical one with five phosphoryl groups in equatorial positions, and a “flipped” conformation with five axial substituents. Using <sup>13</sup>C-labeled InsPs/PP-InsPs, the behavior of these molecules was investigated by 2D-NMR under solution conditions reminiscent of a cytosolic environment. Remarkably, the most highly phosphorylated messenger 1,5(PP)<sub>2</sub>-InsP<sub>4</sub> (also termed InsP<sub>8</sub>) readily adopts both conformations at physiological conditions. Environmental factors—such as pH, metal cation composition, and temperature—strongly influence the conformational equilibrium. Thermodynamic data revealed that the transition of InsP<sub>8</sub> from the equatorial to the axial conformation is, in fact, an exothermic process. The speciation of InsPs and PP-InsPs also affects their interaction with protein binding partners; addition of Mg<sup>2+</sup> decreased the binding constant K<sub>d</sub> of InsP<sub>8</sub> to an SPX protein domain. The results illustrate that PP-InsP speciation reacts very sensitively to solution conditions, suggesting it might act as an environment-responsive molecular switch. |
| first_indexed | 2024-03-11T05:11:50Z |
| format | Article |
| id | doaj.art-37554e8154a8437e9db937f17cf6e3a9 |
| institution | Directory Open Access Journal |
| issn | 2218-273X |
| language | English |
| last_indexed | 2024-03-11T05:11:50Z |
| publishDate | 2023-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Biomolecules |
| spelling | doaj.art-37554e8154a8437e9db937f17cf6e3a92023-11-17T18:29:22ZengMDPI AGBiomolecules2218-273X2023-04-0113464510.3390/biom13040645One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic ConditionsLeonie Kurz0Peter Schmieder1Nicolás Veiga2Dorothea Fiedler3Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125 Berlin, GermanyLeibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125 Berlin, GermanyQuímica Inorgánica, Departamento Estrella Campos, Facultad de Química, Universidad de la República (UdelaR), Av. Gral. Flores 2124, Montevideo 11800, UruguayLeibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Straße 10, 13125 Berlin, GermanyInositol poly- and pyrophosphates (InsPs and PP-InsPs) are central eukaryotic messengers. These very highly phosphorylated molecules can exist in two distinct conformations, a canonical one with five phosphoryl groups in equatorial positions, and a “flipped” conformation with five axial substituents. Using <sup>13</sup>C-labeled InsPs/PP-InsPs, the behavior of these molecules was investigated by 2D-NMR under solution conditions reminiscent of a cytosolic environment. Remarkably, the most highly phosphorylated messenger 1,5(PP)<sub>2</sub>-InsP<sub>4</sub> (also termed InsP<sub>8</sub>) readily adopts both conformations at physiological conditions. Environmental factors—such as pH, metal cation composition, and temperature—strongly influence the conformational equilibrium. Thermodynamic data revealed that the transition of InsP<sub>8</sub> from the equatorial to the axial conformation is, in fact, an exothermic process. The speciation of InsPs and PP-InsPs also affects their interaction with protein binding partners; addition of Mg<sup>2+</sup> decreased the binding constant K<sub>d</sub> of InsP<sub>8</sub> to an SPX protein domain. The results illustrate that PP-InsP speciation reacts very sensitively to solution conditions, suggesting it might act as an environment-responsive molecular switch.https://www.mdpi.com/2218-273X/13/4/645InsP<sub>8</sub>inositol pyrophosphatesconformationNMRring-flipmolecular switch |
| spellingShingle | Leonie Kurz Peter Schmieder Nicolás Veiga Dorothea Fiedler One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions Biomolecules InsP<sub>8</sub> inositol pyrophosphates conformation NMR ring-flip molecular switch |
| title | One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions |
| title_full | One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions |
| title_fullStr | One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions |
| title_full_unstemmed | One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions |
| title_short | One Scaffold, Two Conformations: The Ring-Flip of the Messenger InsP<sub>8</sub> Occurs under Cytosolic Conditions |
| title_sort | one scaffold two conformations the ring flip of the messenger insp sub 8 sub occurs under cytosolic conditions |
| topic | InsP<sub>8</sub> inositol pyrophosphates conformation NMR ring-flip molecular switch |
| url | https://www.mdpi.com/2218-273X/13/4/645 |
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