Cryoelectron tomography reveals doublet-specific structures and unique interactions in the I1 dynein

Thomas Heuser, Cynthia F. Barber, Jianfeng Lin, Jeremy Krell, Matthew Rebesco, Mary E. Porter, Daniela Nicastro

Research output: Contribution to journalArticlepeer-review

80 Scopus citations


Cilia and flagella are highly conserved motile and sensory organelles in eukaryotes, and defects in ciliary assembly and motility cause many ciliopathies. The two-headed I1 inner arm dynein is a critical regulator of ciliary and flagellar beating. To understand I1 architecture and function better, we analyzed the 3D structure and composition of the I1 dynein in Chlamydomonas axonemes by cryoelectron tomography and subtomogram averaging. Our data revealed several connections from the I1 dynein to neighboring structures that are likely to be important for assembly and/or regulation, including a tether linking one I1 motor domain to the doublet microtubule and doublet-specific differences potentially contributing to the asymmetrical distribution of dynein activity required for ciliary beating. We also imaged three I1 mutants and analyzed their polypeptide composition using 2D gel-based proteomics. Structural and biochemical comparisons revealed the likely location of the regulatory IC138 phosphoprotein and its associated subcomplex. Overall, our studies demonstrate that I1 dynein is connected to multiple structures within the axoneme, and therefore ideally positioned to integrate signals that regulate ciliary motility.

Original languageEnglish (US)
Pages (from-to)E2067-E2076
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number30
StatePublished - Jul 24 2012


  • Dynein f
  • Flagella


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