Tetrahymena RIB72A and RIB72B are Microtubule Inner Proteins in the ciliary doublet microtubules

Daniel Stoddard, Ying Zhao, Brian A. Bayless, Long Gui, Panagiota Louka, Drashti Dave, Swati Suryawanshi, Raphaël F.X. Tomasi, Pascale Dupuis-Williams, Charles N. Baroud, Jacek Gaertig, Mark Winey, Daniela Nicastro

Research output: Contribution to journalArticlepeer-review


Doublet and triplet microtubules are essential and highly stable core structures of centrioles, basal bodies, cilia and flagella. In contrast to dynamic cytoplasmic microtubules, their luminal surface is coated with regularly arranged Microtubule Inner Proteins (MIPs). However, the protein composition and biological function(s) of MIPs remain poorly understood. Using genetic, biochemical and imaging techniques we identified Tetrahymena RIB72A and RIB72B proteins as ciliary MIPs. Fluorescence imaging of tagged RIB72A and RIB72B showed that both proteins co-localize to Tetrahymena cilia and basal bodies, but assemble independently. Cryo-electron tomography of RIB72A and/or RIB72B knockout strains revealed major structural defects in the ciliary A-tubule involving MIP1, MIP4 and MIP6 structures. The defects of individual mutants were complementary in the double mutant. All mutants had reduced swimming speed and ciliary beat frequencies, and high-speed video imaging revealed abnormal highly curved cilia during power stroke. Our results show that RIB72A and RIB72B are crucial for the structural assembly of ciliary A-tubule MIPs and are important for proper ciliary motility. SUMMARY Microtubule Inner Proteins (MIPs) bind to the luminal surface of highly stable microtubules. Combining cell biology and cryo-electron tomography, Stoddard et al. show that RIB72A and RIB72B are conserved MIPs in ciliary doublet microtubules and that they are important for proper ciliary motility.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Jun 28 2018

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • Immunology and Microbiology(all)
  • Neuroscience(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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