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Free keywords:
B CORE; EXTRACELLULAR VESICLES; CHLAMYDOMONAS FLAGELLA; TUBULIN
TRANSPORT; SENSORY NEURONS; IMAGE-ANALYSIS; COMPLEX; CILIA; IFT80;
DIFFERENTIATIONLife Sciences & Biomedicine - Other Topics;
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 1.8 angstrom resolution crystal structure of the Chlamydomonas IFT-B protein IFT80, which reveals the architecture of two N-terminal beta-propellers followed by an alpha-helical extension. The N-terminal beta propeller tethers IFT80 to the IFT-B complex via IFT38 whereas the second beta-propeller and the C-terminal alpha-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.
