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Shulin packages axonemal outer dynein arms for ciliary targeting
Girish R Mali1, Ferdos Abid Ali1, Clinton K Lau1
1MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
Science (New York, N.Y.)
|February 26, 2021
Summary
Researchers identified Shulin and Q22MS1 as key factors for transporting outer dynein arms (ODAs) to cilia. Shulin stabilizes ODAs in a compact, inactive state for efficient cytoplasmic transport during ciliogenesis.
Area of Science:
- Cell Biology
- Molecular Motors
- Cilia and Flagella Biology
Background:
- Eukaryotic cilia and flagella rely on axonemal outer dynein arms (ODAs) for force generation.
- These large protein complexes are assembled in the cytoplasm before targeted delivery to cilia, but the mechanism remains unclear.
Purpose of the Study:
- To identify the factors responsible for the cytoplasmic transport of ODAs during ciliogenesis.
- To elucidate the molecular mechanism of ODA packaging and delivery.
Main Methods:
- Utilized the ciliate *Tetrahymena* as a model organism.
- Identified ODA-binding factors using biochemical and genetic approaches.
- Determined the structure of ODA-Shulin complexes via cryo-electron microscopy.
Main Results:
- Two cytoplasmic factors, Q22YU3 (named Shulin) and Q22MS1, were identified as essential for ODA delivery to cilia.
- Shulin binds to ODAs, inhibiting their motor activity by locking the motor domains into a closed conformation.
- Cryo-EM revealed Shulin stabilizes this compact ODA structure through interactions with dynein tails.
Conclusions:
- Shulin and Q22MS1 are crucial for the proper packaging and transport of newly synthesized ODAs.
- The findings provide a molecular basis for how ODAs are prepared for delivery to cilia, ensuring efficient ciliogenesis.
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