The inner junction complex of the cilia is an interaction hub that involves tubulin post-translational modifications
- McGill University, Canada
- Kyoto University, Japan
Abstract
Microtubules are cytoskeletal structures involved in stability, transport and organization in the cell. The building blocks, the α- and β-tubulin heterodimers, form protofilaments that associate laterally into the hollow microtubule. Microtubule also exists as highly stable doublet microtubules in the cilia where stability is needed for ciliary beating and function. The doublet microtubule maintains its stability through interactions at its inner and outer junctions where its A- and B-tubules meet. Here, using cryo-electron microscopy, bioinformatics and mass spectrometry of the doublets of Chlamydomonas reinhardtii and Tetrahymena thermophila, we identified two new inner junction proteins, FAP276 and FAP106, and an inner junction-associated protein, FAP126, thus presenting the complete answer to the inner junction identity and localization. Our structural study of the doublets shows that the inner junction serves as an interaction hub involved tubulin post-translational modification. These interactions contribute to the stability of the doublet and hence, normal ciliary motility.
Data availability
Cryo-EM maps have been deposited in EM data bank (EMDB) with accession numbers of EMD-20855 (48-nm averaged Chlamydomonas doublet), EMD-20858 (16-nm averaged Chlamydomonas IJ region) and EMD-20856 (16-nm averaged Tetrahymena IJ region). The model of IJ of Chlamydomonas is available in Protein Data Bank (PDB) with an accession number of PDB: 6VE7.The mass spectrometry is deposited in DataDryad (doi:10.5061/dryad.d51c59zxt). Available at:https://datadryad.org/stash/share/bkrXp5Ww0iQUis6ocuEya2ivHWQ_YiTFO-VLeIjkQcM
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48-nm repeat unit of the doublet microtubule from Chlamydomonas reinhardtiiElectron Microscopy Data Bank, EMD-20855.
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16-nm averaged Chlamydomonas IJ regionElectron Microscopy Data Bank, EMD-20858.
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16-nm repeat of the doublet microtubule from Tetrahymena thermophilaElectron Microscopy Data Bank, EMD-20856.
Article and author information
Author details
Funding
Canadian Institutes of Health Research (PJT-156354)
- Khanh Huy Bui
Natural Sciences and Engineering Research Council of Canada (RGPIN-2016-04954)
- Khanh Huy Bui
Natural Sciences and Engineering Research Council of Canada (RGPIN-2018-04813)
- Javier Vargas
Canada Institute For Advanced Research (Arzieli Global Scholar Program)
- Khanh Huy Bui
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Khalifa et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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The inner junction complex of the cilia is an interaction hub that involves tubulin post-translational modifications
eLife 9:e52760.
https://doi.org/10.7554/eLife.52760
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