Dynein-decorated doublet microtubules (DMTs) are critical components of the oscillatory molecular machine of cilia, the axoneme, and have luminal surfaces patterned periodically by microtubule inner proteins (MIPs). Here we present an atomic model of the 48-nm repeat of a mammalian DMT, derived from a cryoelectron microscopy (cryo-EM) map of the complex isolated from bovine respiratory cilia. The structure uncovers principles of doublet microtubule organization and features specific to vertebrate cilia, including previously unknown MIPs, a luminal bundle of tektin filaments, and a pentameric dynein-docking complex. We identify a mechanism for bridging 48- to 24-nm periodicity across the microtubule wall and show that loss of the proteins involved causes defective ciliary motility and laterality abnormalities in zebrafish and mice. Our structure identifies candidate genes for diagnosis of ciliopathies and provides a framework to understand their functions in driving ciliary motility.
Organizational Affiliation:
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
MRC Harwell Institute, Harwell Campus, Oxfordshire OX11 0RD, UK.
Institute of Molecular and Cell Biology, Proteos, 138673 Singapore, Singapore; Department of Infection, Immunity & Cardiovascular Disease, The Medical School and The Florey Institute for Host Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, UK.
Institute of Molecular and Cell Biology, Proteos, 138673 Singapore, Singapore; School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK.
Institute of Molecular and Cell Biology, Proteos, 138673 Singapore, Singapore.
Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
Biomedical Imaging Unit, Southampton General Hospital, Southampton, UK; Primary Ciliary Dyskinesia Centre, NIHR Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK.
Primary Ciliary Dyskinesia Centre, NIHR Biomedical Research Centre, University Hospital Southampton NHS Foundation Trust, Southampton, UK; University of Southampton Faculty of Medicine, School of Clinical and Experimental Medicine, Southampton, UK.
Department of Infection, Immunity & Cardiovascular Disease, The Medical School and The Florey Institute for Host Pathogen Interactions, University of Sheffield, Sheffield S10 2TN, UK.
Institute of Molecular and Cell Biology, Proteos, 138673 Singapore, Singapore; Department of Biological Sciences, National University of Singapore, 117543 Singapore, Singapore; Department of Pediatrics, Yong Loo Ling School of Medicine, National University of Singapore, 1E Kent Ridge Road, 119288 Singapore, Singapore. Electronic address: sudipto@imcb.a-star.edu.sg.
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. Electronic address: alan_brown@hms.harvard.edu.
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