Unwrapping the ciliary coat: high-resolution structure and function of the ciliary glycocalyx

Hoepfner, L. M.; Nievergelt, A. P.; Martino, F.; Scholz, M.; Foster, H. E.; Rodenfels, J.; von Appen, A.; Hippler, M.; Pigino, G.

doi:10.1101/2024.09.28.615573

bioRxiv · 10.1101/2024.09.28.615573

Unwrapping the ciliary coat: high-resolution structure and function of the ciliary glycocalyx

Hoepfner, L. M.·Nievergelt, A. P.·Martino, F.·Scholz, M.·Foster, H. E.·Rodenfels, J.·von Appen, A.·Hippler, M.·Pigino, G.

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Abstract

The glycocalyx, a highly heterogeneous glycoprotein layer of cilia regulates adhesion and force transduction, and is involved in signalling. The high-resolution molecular architecture of this layer is currently not understood. We describe the structure of the ciliary coat in the green alga Chlamydomonas reinhardtii by cryo-electron tomography and proteomic approaches and present the high-resolution cryoEM structure of the main component, FMG1B. We describe FMG1B as a mucin orthologue which lacks the major O-glycosylation of mammalian mucins, but is N-glycosylated. FMG1A, a previously undescribed isoform of FMG1B is expressed in C. reinhardtii. By microflow-based adhesion assays we observe increased surface adhesion in the glycocalyx deficient double-mutant fmg1a-fmg1b. We find this mutant to be capable of surface-gliding, with neither isoform required for extracellular force transduction by intraflagellar transport. Our results find FMG1 to form a protective layer with adhesion-regulative instead of adhesion-conferring properties and an example of an undescribed class of mucins.

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Hoepfner, L. M., Nievergelt, A. P., Martino, F., Scholz, M., Foster, H. E., Rodenfels, J., von Appen, A., Hippler, M., Pigino, G.. 2024-09-29. Unwrapping the ciliary coat: high-resolution structure and function of the ciliary glycocalyx. https://doi.org/10.1101/2024.09.28.615573

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