The Chlamydomonas mutant pf27 reveals novel features of ciliary radial spoke assembly. Issue 12 (29th October 2013)

• Record Type: Journal Article
• Authors: Alford, Lea M.; Mattheyses, Alexa L.; Hunter, Emily L.; Lin, Huawen; Dutcher, Susan K.; Sale, Winfield S.
• Is Part Of: Cytoskeleton. Volume 70:Issue 12(2013:Dec.)
• Page Start: 804
• Page End: 818
• Publication Date: 2013-10-29
• Subjects: Cytoskeleton -- Periodicals; 571.65405
• DOI: 10.1002/cm.21144
• Languages: English
• ISSNs: 1949-3584

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>To address the mechanisms of ciliary radial spoke assembly, we took advantage of the <italic>Chlamydomonas pf27</italic> mutant. The radial spokes that assemble in <italic>pf27</italic> are localized to the proximal quarter of the axoneme, but otherwise are fully assembled into 20S radial spoke complexes competent to bind spokeless axonemes <italic>in vitro</italic>. Thus, <italic>pf27</italic> is not defective in radial spoke assembly or docking to the axoneme. Rather, our results suggest that <italic>pf27</italic> is defective in the transport of spoke complexes. During ciliary regeneration in <italic>pf27</italic>, radial spoke assembly occurs asynchronously from other axonemal components. In contrast, during ciliary regeneration in wild‐type <italic>Chlamydomonas</italic>, radial spokes and other axonemal components assemble concurrently as the axoneme grows. Complementation in temporary dikaryons between wild‐type and <italic>pf27</italic> 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 <italic>pf27</italic> axonemes in dikaryons. These results reveal that 20S radial spokes can assemble proximally in the <italic>pf27</italic> cilium but as the cilium lengthens, spoke assembly requires transport. We postulate that <italic>PF27</italic> encodes an adaptor or modifier protein required for radial spoke–IFT interaction. © 2013 Wiley Periodicals, Inc.</p> </abstract>