Crystal structure of intraflagellar transport protein 80 reveals a homo-dimer required for ciliogenesis

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Abstract

Oligomeric assemblies of intraflagellar transport (IFT) particles build cilia through sequential recruitment and transport of ciliary cargo proteins within cilia. Here we present the 1.8Å resolution crystal structure of the Chlamydomonas IFT-B protein IFT80, which reveals the architecture of two N-terminal b-propellers followed by an a-helical extension. The N-terminal b-propeller tethers IFT80 to the IFT-B complex via IFT38 whereas the second b-propeller and the C-terminal a-helical extension result in IFT80 homo-dimerization. Using CRISPR/Cas to create biallelic Ift80 frameshift mutations in IMCD3 mouse cells, we demonstrate that IFT80 is absolutely required for ciliogenesis. Structural mapping and rescue experiments reveal that human disease-causing missense mutations do not cluster within IFT80 and form functional IFT particles. Unlike missense mutant forms of IFT80, deletion of the C-terminal dimerization domain prevented rescue of ciliogenesis. Taken together our results may provide a first insight into higher order IFT complex formation likely required for IFT train formation.

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The structural coordinates for IFT80 and diffraction data have been uploaded to the protein data bank (PDB).Macros used for data analysis are available for download through links provided in the material and methods part of the manuscript.

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Michael Taschner

Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark

Competing interests
The authors declare that no competing interests exist.
Anna Lorentzen

Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark

Competing interests
The authors declare that no competing interests exist.
André Mourão

Institute of Structural Biology, Helmholtz Zentrum München, Neuherberg, Germany

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The authors declare that no competing interests exist.
Toby Collins

Genetics and Genomic Medicine, University College London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Grace M Freke

Genetics and Genomic Medicine, University College London, London, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Dale Moulding

Developmental Biology and Cancer Programmes, University College London, London, United Kingdom

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The authors declare that no competing interests exist.
Jerome Basquin

Department of Structural Cell Biology, Max Planck Institute of Biochemistry, Martinsried, Germany

Competing interests
The authors declare that no competing interests exist.
Dagan Jenkins

Genetics and Genomic Medicine, University College London, London, United Kingdom

For correspondence
d.jenkins@ucl.ac.uk

Competing interests
The authors declare that no competing interests exist.
Esben Lorentzen

Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark

For correspondence
el@mbg.au.dk

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0001-6493-7220

Funding

Novo Nordisk (NNF15OC00114164)

Esben Lorentzen

Medical Research Council (MR/L009978/1)

Dagan Jenkins

Biotechnology and Biological Sciences Research Council (STU100044631)

Dagan Jenkins

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.