2001 Fiscal Year Final Research Report Summary
The role of multiple ATP-binding sites in dynein motor domain
| Project/Area Number |
12480196
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biophysics
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TOYOSHIMA Yoko The University of Tokyo, Graduate School of Arts and Sciences, Associate Professor, 大学院・総合文化研究科, 助教授 (40158043)
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| Co-Investigator(Kenkyū-buntansha) |
EDAMATSU Masaki The University of Tokyo, Graduate School of Arts and Sciences, Research Assistant, 大学院・総合文化研究科, 助手 (60251328)
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| Project Period (FY) |
2000 – 2001
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| Keywords | dynein / ATP binding site / P-loops / Tetrahyemena / inner arms / monomeric dynein / microtubules / Michaelis-Menten |
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| Research Abstract |
Dynein is a huge complex molecule including heavy chain(s) which have multiple (4) ATP binding consensus sequences (P-loops) as well as intermediate and light chains. We purified a monomeric form of dynein (dynein-a) from 14S dyneins of Tetrahymena thermophila and characterized it. In in vitro motility assays, dynein-a rotated microtubules around their longitudinal axis as well as translocated them with their plus-ends leading. ATPase activity at 1 mM ATP was doubled in the presence of a low level of ADP. Both ATPase activity and transnational velocities in the presence of ADP fit the Michaelis- Menten equation well. However in the absence of ADP, neither of the activities followed the Michaelis-Menten-type kinetics probably due to the effect of two-ATP binding sites. Our results also indicate that dynein-a has an ATP-binding site that is very sensitive to ADP and affects ATP hydrolysis at the catalytic site. This study shows that a monomeric form of dynein molecule regulates its activity by direct binding of ATP and ADP to itself, and thus the dynein molecule has an intramolecular regulating system.
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