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Mutant kinesin-2 motor subunits increase chromosome loss
Mark S Miller1, Jessica M Esparza, Andrew M Lippa
1Department of Microbiology, Molecular Biology, and Biochemistry, University of Idaho, Moscow, ID 83844-3052, USA.
Molecular Biology of the Cell
|June 10, 2005
Summary
The kinesin-2 motor complex in Chlamydomonas is crucial for flagellar assembly and chromosome segregation. Mutations in its motor subunits reveal a pocket essential for motor function and maintaining chromosome fidelity.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Intraflagellar transport (IFT) is essential for flagellar assembly and function.
- Kinesin-2 is a key motor protein complex involved in anterograde IFT in Chlamydomonas.
Purpose of the Study:
- To characterize the kinesin-2 motor complex in Chlamydomonas.
- To investigate the role of specific motor subunits in flagellar assembly and chromosome segregation.
Main Methods:
- Mass spectrometry and sequencing to identify motor subunits.
- Genetic analysis of temperature-sensitive mutants (fla1, fla8) and intragenic revertants.
- Characterization of point mutations within the motor domain.
Main Results:
- Identified a second kinesin-2 motor subunit with significant homology to Fla10.
- Mutations in this subunit (fla1, fla8) cause temperature-sensitive flagellar defects and a chromosome loss phenotype.
- Analysis revealed a conserved pocket in the motor subunit's N-terminus critical for motor activity and chromosome segregation fidelity.
Conclusions:
- The kinesin-2 motor complex plays a dual role in flagellar assembly and accurate chromosome segregation.
- A specific structural feature (N-terminal pocket) in the motor subunits is vital for both functions.
- This study highlights a novel link between IFT motor proteins and chromosome segregation fidelity.