Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends
GTP-tubulin is preferentially incorporated at growing microtubule ends, but the biochemical mechanism by which the bound nucleotide regulates the strength of tubulin:tubulin interactions is debated. The ‘self-acting’ (cis) model posits that the nucleotide (GTP or GDP) bound to a particular tubulin d...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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eLife Sciences Publications Ltd
2024-01-01
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| Series: | eLife |
| Subjects: | |
| Online Access: | https://elifesciences.org/articles/89231 |
| _version_ | 1827290223911895040 |
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| author | Lauren A McCormick Joseph M Cleary William O Hancock Luke M Rice |
| author_facet | Lauren A McCormick Joseph M Cleary William O Hancock Luke M Rice |
| author_sort | Lauren A McCormick |
| collection | DOAJ |
| description | GTP-tubulin is preferentially incorporated at growing microtubule ends, but the biochemical mechanism by which the bound nucleotide regulates the strength of tubulin:tubulin interactions is debated. The ‘self-acting’ (cis) model posits that the nucleotide (GTP or GDP) bound to a particular tubulin dictates how strongly that tubulin interacts, whereas the ‘interface-acting’ (trans) model posits that the nucleotide at the interface of two tubulin dimers is the determinant. We identified a testable difference between these mechanisms using mixed nucleotide simulations of microtubule elongation: with a self-acting nucleotide, plus- and minus-end growth rates decreased in the same proportion to the amount of GDP-tubulin, whereas with interface-acting nucleotide, plus-end growth rates decreased disproportionately. We then experimentally measured plus- and minus-end elongation rates in mixed nucleotides and observed a disproportionate effect of GDP-tubulin on plus-end growth rates. Simulations of microtubule growth were consistent with GDP-tubulin binding at and ‘poisoning’ plus-ends but not at minus-ends. Quantitative agreement between simulations and experiments required nucleotide exchange at terminal plus-end subunits to mitigate the poisoning effect of GDP-tubulin there. Our results indicate that the interfacial nucleotide determines tubulin:tubulin interaction strength, thereby settling a longstanding debate over the effect of nucleotide state on microtubule dynamics. |
| first_indexed | 2024-03-08T15:25:32Z |
| format | Article |
| id | doaj.art-68fe5f499f9a438da74d307b30dd5768 |
| institution | Directory Open Access Journal |
| issn | 2050-084X |
| language | English |
| last_indexed | 2024-04-24T12:12:29Z |
| publishDate | 2024-01-01 |
| publisher | eLife Sciences Publications Ltd |
| record_format | Article |
| series | eLife |
| spelling | doaj.art-68fe5f499f9a438da74d307b30dd57682024-04-08T11:12:06ZengeLife Sciences Publications LtdeLife2050-084X2024-01-011210.7554/eLife.89231Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-endsLauren A McCormick0https://orcid.org/0000-0001-9164-0932Joseph M Cleary1https://orcid.org/0000-0003-0879-2543William O Hancock2https://orcid.org/0000-0001-5547-8755Luke M Rice3https://orcid.org/0000-0001-6551-3307Department of Biophysics and Biochemistry, the University of Texas Southwestern Medical Center, Dallas, United StatesDepartment of Biomedical Engineering, Pennsylvania State University, State College, United StatesDepartment of Biomedical Engineering, Pennsylvania State University, State College, United StatesDepartment of Biophysics and Biochemistry, the University of Texas Southwestern Medical Center, Dallas, United StatesGTP-tubulin is preferentially incorporated at growing microtubule ends, but the biochemical mechanism by which the bound nucleotide regulates the strength of tubulin:tubulin interactions is debated. The ‘self-acting’ (cis) model posits that the nucleotide (GTP or GDP) bound to a particular tubulin dictates how strongly that tubulin interacts, whereas the ‘interface-acting’ (trans) model posits that the nucleotide at the interface of two tubulin dimers is the determinant. We identified a testable difference between these mechanisms using mixed nucleotide simulations of microtubule elongation: with a self-acting nucleotide, plus- and minus-end growth rates decreased in the same proportion to the amount of GDP-tubulin, whereas with interface-acting nucleotide, plus-end growth rates decreased disproportionately. We then experimentally measured plus- and minus-end elongation rates in mixed nucleotides and observed a disproportionate effect of GDP-tubulin on plus-end growth rates. Simulations of microtubule growth were consistent with GDP-tubulin binding at and ‘poisoning’ plus-ends but not at minus-ends. Quantitative agreement between simulations and experiments required nucleotide exchange at terminal plus-end subunits to mitigate the poisoning effect of GDP-tubulin there. Our results indicate that the interfacial nucleotide determines tubulin:tubulin interaction strength, thereby settling a longstanding debate over the effect of nucleotide state on microtubule dynamics.https://elifesciences.org/articles/89231microtubule dynamicsmixed nucleotidekinetic simulations |
| spellingShingle | Lauren A McCormick Joseph M Cleary William O Hancock Luke M Rice Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends eLife microtubule dynamics mixed nucleotide kinetic simulations |
| title | Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends |
| title_full | Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends |
| title_fullStr | Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends |
| title_full_unstemmed | Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends |
| title_short | Interface-acting nucleotide controls polymerization dynamics at microtubule plus- and minus-ends |
| title_sort | interface acting nucleotide controls polymerization dynamics at microtubule plus and minus ends |
| topic | microtubule dynamics mixed nucleotide kinetic simulations |
| url | https://elifesciences.org/articles/89231 |
| work_keys_str_mv | AT laurenamccormick interfaceactingnucleotidecontrolspolymerizationdynamicsatmicrotubuleplusandminusends AT josephmcleary interfaceactingnucleotidecontrolspolymerizationdynamicsatmicrotubuleplusandminusends AT williamohancock interfaceactingnucleotidecontrolspolymerizationdynamicsatmicrotubuleplusandminusends AT lukemrice interfaceactingnucleotidecontrolspolymerizationdynamicsatmicrotubuleplusandminusends |