Document Detail


A simple theoretical model explains dynein's response to load.
MedLine Citation:
PMID:  16284275     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Recent experiment showed that cytoplasmic dynein 1, a molecular motor responsible for cargo transport in cells, functions as a gear in response to external load. In the presence of vanishing or small external load, dynein walks with 24- or 32-nm steps, whereas at high external load, its step size is reduced to 8 nm. A simple model is proposed to account for this property of dynein. The model assumes that the chemical energy of ATP hydrolysis is used through a loose coupling between the chemical reaction and the translocation of dynein along microtubule. This loose chemomechanical coupling is represented by the loosely coupled motions of dynein along two different reaction coordinates. The first reaction coordinate is tightly coupled to the chemical reaction and describes the protein conformational changes that control the chemical processes, including ATP binding and hydrolysis, and ADP-Pi release. The second coordinate describes the translocation of dynein along microtubule, which is directly subject to the influence of the external load. The model is used to explain the experimental data on the external force dependence of the dynein step size as well as the ATP concentration dependence of the stall force. A number of predictions, such as the external force dependence of speed of translocation, ATP hydrolysis rate, and dynein step sizes, are made based on this theoretical model. This model provides a simple understanding on how a variable chemomechanical coupling ratio can be achieved and used to optimize the biological function of dynein.
Authors:
Yi Qin Gao
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-11-11
Journal Detail:
Title:  Biophysical journal     Volume:  90     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  2006 Feb 
Date Detail:
Created Date:  2006-01-13     Completed Date:  2006-05-17     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  811-21     Citation Subset:  IM    
Affiliation:
Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA. yiqin@mail.chem.tamu.edu
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MeSH Terms
Descriptor/Qualifier:
Adenosine Diphosphate / chemistry
Adenosine Triphosphate / chemistry*
Animals
Binding Sites
Biophysics / methods*
Cytoplasm / metabolism
Diffusion
Dyneins / chemistry*
Hydrolysis
Kinesin / chemistry
Kinetics
Microtubules
Models, Biological
Models, Chemical
Models, Statistical
Molecular Conformation
Molecular Motor Proteins / chemistry
Movement
Phosphates / chemistry
Protein Binding
Protein Transport
Stress, Mechanical
Thermodynamics
Time Factors
Chemical
Reg. No./Substance:
0/Molecular Motor Proteins; 0/Phosphates; 56-65-5/Adenosine Triphosphate; 58-64-0/Adenosine Diphosphate; EC 3.6.1.-/Kinesin; EC 3.6.4.2/Dyneins
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