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J Cell Biol. 2019 Oct 31. pii: jcb.201906006. doi: 10.1083/jcb.201906006. [Epub ahead of print]

Structural organization of the C1a-e-c supercomplex within the ciliary central apparatus.

Author information

1
Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX.
2
Department of Radiology, Division of Cell Biology and Imaging, University of Massachusetts Medical School, Worcester, MA.
3
Department of Biological Sciences, Dartmouth College, Hanover, NH.
4
Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX daniela.nicastro@utsouthwestern.edu.
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Contributed equally

Abstract

Nearly all motile cilia contain a central apparatus (CA) composed of two connected singlet microtubules with attached projections that play crucial roles in regulating ciliary motility. Defects in CA assembly usually result in motility-impaired or paralyzed cilia, which in humans causes disease. Despite their importance, the protein composition and functions of the CA projections are largely unknown. Here, we integrated biochemical and genetic approaches with cryo-electron tomography to compare the CA of wild-type Chlamydomonas with CA mutants. We identified a large (>2 MD) complex, the C1a-e-c supercomplex, that requires the PF16 protein for assembly and contains the CA components FAP76, FAP81, FAP92, and FAP216. We localized these subunits within the supercomplex using nanogold labeling and show that loss of any one of them results in impaired ciliary motility. These data provide insight into the subunit organization and 3D structure of the CA, which is a prerequisite for understanding the molecular mechanisms by which the CA regulates ciliary beating.

PMID:
31672705
DOI:
10.1083/jcb.201906006

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