Diffusion rather than IFT provides most of the tubulin required for axonemal assembly

Harris, J. A.; Van De Weghe, J. M.; Kubo, T.; Witman, G. B.; Lechtreck, K.

doi:10.1101/268573

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bioRxiv · 10.1101/268573

Diffusion rather than IFT provides most of the tubulin required for axonemal assembly

Harris, J. A.·Van De Weghe, J. M.·Kubo, T.·Witman, G. B.·Lechtreck, K.

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Abstract

Tubulin enters the cilia by diffusion and motor-based intraflagellar transport (IFT). The respective contributions of each route in providing tubulin for axonemal assembly are unknown. To attenuate IFT-based transport, we expressed modified GFP-tubulins in strains possessing IFT81 and IFT74 with altered tubulin binding sites. E-hook deficient GFP-{beta}-tubulin normally incorporated into the axonemal microtubules; its transport frequency was reduced by ~90% in control cells and essentially abolished when expressed in a strain possessing IFT81 with an incapacitated tubulin-binding site. Despite the strong reduction in IFT, the share of E-hook deficient GFP-{beta}-tubulin in the axoneme was only moderately reduced indicating that most axonemal tubulin (~80%) enters cilia by diffusion. While not providing the bulk of axonemal tubulin, we propose that motor-based IFT is nevertheless critical for ciliogenesis because it ensures high concentrations of tubulin near the ciliary tip promoting axonemal elongation.

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Harris, J. A., Van De Weghe, J. M., Kubo, T., Witman, G. B., Lechtreck, K.. 2018-02-20. Diffusion rather than IFT provides most of the tubulin required for axonemal assembly. https://doi.org/10.1101/268573

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