Subunit Interactions and Cooperativity in the Microtubule-severing AAA ATPase Spastin*
| Autor: | Susanne Link, Klaus Richter, Anja Gieseke, Jean-Philippe Sobczak, Thomas Eckert, Doan Tuong-Van Le, Guenther Woehlke |
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| Jazyk: | angličtina |
| Rok vydání: | 2012 |
| Předmět: |
Spastin
Swine ATPase Protein subunit Allosteric regulation Mutation Missense Cooperativity macromolecular substances Biology Biochemistry environment and public health Microtubules Time-Lapse Imaging Adenosine Triphosphate Microtubule Animals Humans Protein Structure Quaternary Molecular Biology Microtubule severing Enzyme Assays Sequence Deletion Adenosine Triphosphatases musculoskeletal neural and ocular physiology Hydrolysis Cell Biology musculoskeletal system AAA proteins Kinetics Protein Subunits nervous system biology.protein Biophysics Enzymology Protein Multimerization Algorithms Protein Binding |
| Popis: | Spastin is a hexameric ring AAA ATPase that severs microtubules. To see whether the ring complex funnels the energy of multiple ATP hydrolysis events to the site of mechanical action, we investigate here the cooperativity of spastin. Several lines of evidence indicate that interactions among two subunits dominate the cooperative behavior: (i) the ATPase activity shows a sigmoidal dependence on the ATP concentration; (ii) ATPγS displays a mixed-inhibition behavior for normal ATP turnover; and (iii) inactive mutant subunits inhibit the activity of spastin in a hyperbolic dependence, characteristic for two interacting species. A quantitative model based on neighbor interactions fits mutant titration experiments well, suggesting that each subunit is mainly influenced by one of its neighbors. These observations are relevant for patients suffering from SPG4-type hereditary spastic paraplegia and explain why single amino acid exchanges lead to a dominant negative phenotype. In severing assays, wild type spastin is even more sensitive toward the presence of inactive mutants than in enzymatic assays, suggesting a weak coupling of ATPase and severing activity. |
| Databáze: | OpenAIRE |
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