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
-
48-nm repeat unit of the doublet microtubule from Chlamydomonas reinhardtiiElectron Microscopy Data Bank, EMD-20855.
-
16-nm averaged Chlamydomonas IJ regionElectron Microscopy Data Bank, EMD-20858.
-
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.
Reviewing Editor
- Andrew P Carter, MRC Laboratory of Molecular Biology, United Kingdom
Version history
- Received: October 15, 2019
- Accepted: January 16, 2020
- Accepted Manuscript published: January 17, 2020 (version 1)
- Version of Record published: January 31, 2020 (version 2)
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.
Metrics
-
- 3,746
- views
-
- 540
- downloads
-
- 1,227
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
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
Further reading
-
- Biochemistry and Chemical Biology
- Structural Biology and Molecular Biophysics
The articles in this special issue highlight how modern cellular, biochemical, biophysical and computational techniques are allowing deeper and more detailed studies of allosteric kinase regulation.
-
- Developmental Biology
- Structural Biology and Molecular Biophysics
The receptor tyrosine kinase ROR2 mediates noncanonical WNT5A signaling to orchestrate tissue morphogenetic processes, and dysfunction of the pathway causes Robinow syndrome, brachydactyly B, and metastatic diseases. The domain(s) and mechanisms required for ROR2 function, however, remain unclear. We solved the crystal structure of the extracellular cysteine-rich (CRD) and Kringle (Kr) domains of ROR2 and found that, unlike other CRDs, the ROR2 CRD lacks the signature hydrophobic pocket that binds lipids/lipid-modified proteins, such as WNTs, suggesting a novel mechanism of ligand reception. Functionally, we showed that the ROR2 CRD, but not other domains, is required and minimally sufficient to promote WNT5A signaling, and Robinow mutations in the CRD and the adjacent Kr impair ROR2 secretion and function. Moreover, using function-activating and -perturbing antibodies against the Frizzled (FZ) family of WNT receptors, we demonstrate the involvement of FZ in WNT5A-ROR signaling. Thus, ROR2 acts via its CRD to potentiate the function of a receptor super-complex that includes FZ to transduce WNT5A signals.
