Calaxin stabilizes the docking of outer arm dyneins onto ciliary doublet microtubule in vertebrates

Elife. 2023 Apr 14:12:e84860. doi: 10.7554/eLife.84860.

Abstract

Outer arm dynein (OAD) is the main force generator of ciliary beating. Although OAD loss is the most frequent cause of human primary ciliary dyskinesia, the docking mechanism of OAD onto the ciliary doublet microtubule (DMT) remains elusive in vertebrates. Here, we analyzed the functions of Calaxin/Efcab1 and Armc4, the two of five components of vertebrate OAD-DC (docking complex), using zebrafish spermatozoa and cryo-electron tomography. Mutation of armc4 caused complete loss of OAD, whereas mutation of calaxin caused only partial loss of OAD. Detailed structural analysis revealed that calaxin-/- OADs are tethered to DMT through DC components other than Calaxin, and that recombinant Calaxin can autonomously rescue the deficient DC structure and the OAD instability. Our data demonstrate the discrete roles of Calaxin and Armc4 in the OAD-DMT interaction, suggesting the stabilizing process of OAD docking onto DMT in vertebrates.

Keywords: axoneme; calaxin; cell biology; cilia; cryo-ET; dynein; molecular biophysics; sperm; structural biology; zebrafish.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Armadillo Domain Proteins / genetics
  • Armadillo Domain Proteins / metabolism
  • Axoneme / metabolism
  • Cilia* / genetics
  • Cilia* / metabolism
  • Cryoelectron Microscopy
  • Cytoskeletal Proteins* / genetics
  • Cytoskeletal Proteins* / metabolism
  • Dyneins* / metabolism
  • Male
  • Microscopy, Fluorescence
  • Microtubules* / metabolism
  • Models, Molecular
  • Mutation
  • Protein Stability
  • Spermatozoa / metabolism
  • Zebrafish* / genetics

Substances

  • Dyneins
  • Efcab1 protein, zebrafish
  • Cytoskeletal Proteins
  • Armadillo Domain Proteins

Grants and funding

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.