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Poghosyan E, Iacovache I, Faltova L, Leitner A, Yang P, Diener DR, Aebersold R, Zuber B, Ishikawa T. The structure and symmetry of the radial spoke protein complex in Chlamydomonas flagella. J Cell Sci 2020; 133:jcs245233. [PMID: 32694165 DOI: 10.1242/jcs.245233] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 06/25/2020] [Indexed: 12/27/2022] Open
Abstract
The radial spoke is a key element in a transducer apparatus controlling the motility of eukaryotic cilia. The transduction biomechanics is a long-standing question in cilia biology. The radial spoke has three regions - a spoke head, a bifurcated neck and a stalk. Although the neck and the stalk are asymmetric, twofold symmetry of the head has remained controversial. In this work we used single particle cryo-electron microscopy (cryo-EM) analysis to generate a 3D structure of the whole radial spoke at unprecedented resolution. We show the head region at 15 Å (1.5 nm) resolution and confirm twofold symmetry. Using distance constraints generated by cross-linking mass spectrometry, we locate two components, RSP2 and RSP4, at the head and neck regions. Our biophysical analysis of isolated RSP4, RSP9, and RSP10 affirmed their oligomeric state. Our results enable us to redefine the boundaries of the regions and propose a model of organization of the radial spoke component proteins.
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Affiliation(s)
- Emiliya Poghosyan
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
- ETH Zurich, Department of Biology, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
| | - Ioan Iacovache
- University of Bern, Institute of Anatomy, Baltzerstrasse 2, 3012 Bern, Switzerland
| | - Lenka Faltova
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Alexander Leitner
- ETH Zurich, Department of Biology, Institute of Molecular Systems Biology, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
| | - Pinfen Yang
- Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA
| | - Dennis R Diener
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
| | - Ruedi Aebersold
- ETH Zurich, Department of Biology, Institute of Molecular Systems Biology, Otto-Stern-Weg 3, 8093 Zürich, Switzerland
- University of Zurich, Faculty of Science, Rämistrasse 71, 8006 Zürich, Switzerland
| | - Benoit Zuber
- University of Bern, Institute of Anatomy, Baltzerstrasse 2, 3012 Bern, Switzerland
| | - Takashi Ishikawa
- Paul Scherrer Institute, Department of Biology and Chemistry, Forschungsstrasse 111, 5232 Villigen PSI, Switzerland
- ETH Zurich, Department of Biology, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland
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Alford LM, Mattheyses AL, Hunter EL, Lin H, Dutcher SK, Sale WS. The Chlamydomonas mutant pf27 reveals novel features of ciliary radial spoke assembly. Cytoskeleton (Hoboken) 2014; 70:804-18. [PMID: 24124175 DOI: 10.1002/cm.21144] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 09/10/2013] [Accepted: 09/12/2013] [Indexed: 01/05/2023]
Abstract
To address the mechanisms of ciliary radial spoke assembly, we took advantage of the Chlamydomonas pf27 mutant. The radial spokes that assemble in pf27 are localized to the proximal quarter of the axoneme, but otherwise are fully assembled into 20S radial spoke complexes competent to bind spokeless axonemes in vitro. Thus, pf27 is not defective in radial spoke assembly or docking to the axoneme. Rather, our results suggest that pf27 is defective in the transport of spoke complexes. During ciliary regeneration in pf27, radial spoke assembly occurs asynchronously from other axonemal components. In contrast, during ciliary regeneration in wild-type Chlamydomonas, radial spokes and other axonemal components assemble concurrently as the axoneme grows. Complementation in temporary dikaryons between wild-type and pf27 reveals rescue of radial spoke assembly that begins at the distal tip, allowing further assembly to proceed from tip to base of the axoneme. Notably, rescued assembly of radial spokes occurred independently of the established proximal radial spokes in pf27 axonemes in dikaryons. These results reveal that 20S radial spokes can assemble proximally in the pf27 cilium but as the cilium lengthens, spoke assembly requires transport. We postulate that PF27 encodes an adaptor or modifier protein required for radial spoke–IFT interaction.
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Craige B, Brown JM, Witman GB. Isolation of Chlamydomonas flagella. CURRENT PROTOCOLS IN CELL BIOLOGY 2013; Chapter 3:3.41.1-3.41.9. [PMID: 23728744 PMCID: PMC3937870 DOI: 10.1002/0471143030.cb0341s59] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A simple, scalable, and fast procedure for the isolation of Chlamydomonas flagella is described. Chlamydomonas can be synchronously deflagellated by treatment with chemicals, pH shock, or mechanical shear. The Basic Protocol describes the procedure for flagellar isolation using dibucaine to induce flagellar abscission; we also describe the pH shock method as an Alternate Protocol when flagellar regeneration is desirable. Sub-fractionation of the isolated flagella into axonemes and the membrane + matrix fraction is described in a Support Protocol.
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Affiliation(s)
- Branch Craige
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jason M. Brown
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - George B. Witman
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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Dymek EE, Heuser T, Nicastro D, Smith EF. The CSC is required for complete radial spoke assembly and wild-type ciliary motility. Mol Biol Cell 2011; 22:2520-31. [PMID: 21613541 PMCID: PMC3135477 DOI: 10.1091/mbc.e11-03-0271] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Structural and functional analyses of artificial micro RNA (amiRNA) mutants reveal that the CSC plays a role not only in generating wild-type motility, but also in assembly of at least a subset of radial spokes. This study also produced the unexpected finding that, contrary to current belief, the radial spokes may not be homogeneous. The ubiquitous calcium binding protein, calmodulin (CaM), plays a major role in regulating the motility of all eukaryotic cilia and flagella. We previously identified a CaM and Spoke associated Complex (CSC) and provided evidence that this complex mediates regulatory signals between the radial spokes and dynein arms. We have now used an artificial microRNA (amiRNA) approach to reduce expression of two CSC subunits in Chlamydomonas. For all amiRNA mutants, the entire CSC is lacking or severely reduced in flagella. Structural studies of mutant axonemes revealed that assembly of radial spoke 2 is defective. Furthermore, analysis of both flagellar beating and microtubule sliding in vitro demonstrates that the CSC plays a critical role in modulating dynein activity. Our results not only indicate that the CSC is required for spoke assembly and wild-type motility, but also provide evidence for heterogeneity among the radial spokes.
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Affiliation(s)
- Erin E Dymek
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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