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bioRxiv · 10.1101/2021.09.13.460064

High interaction valency ensures cohesion and persistence of a microtubule +TIP body at the plus-end of a single specialized microtubule in yeast

Meier, S. M.·Farcas, A.-M.·Kumar, A.·Ijavi, M.·Bill, R.·Stelling, J.·Dufresne, E. R.·Steinmetz, M. O.·Barral, Y.
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Abstract

Microtubule plus-end tracking proteins (+TIPs) control microtubule specialization and are as such essential notably during eukaryotic cell division. Here, we investigated interactions and functions of the budding yeast Kar9 network consisting of the core +TIPs components Kar9 (functional homologue of APC, MACF, and SLAIN), Bim1 (orthologue of EB1), and Bik1 (orthologue of CLIP-170). Our data indicate that a redundant, multivalent web of interactions links the three +TIPs together to form a "Kar9 body" at the tip of a single cytoplasmic microtubule. They further suggest that this body is a liquid-like condensate, allowing it to persist on both growing and shrinking microtubule tips, and functions as a mechanical coupling device between microtubules and actin cables during mitosis. Our study underlines the power of dissecting the web of low-affinity interactions driving liquid-liquid phase separation of proteins in order to demonstrate the importance and establish the functional roles of condensation processes in vivo.

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Meier, S. M., Farcas, A.-M., Kumar, A., Ijavi, M., Bill, R., Stelling, J., Dufresne, E. R., Steinmetz, M. O., Barral, Y.. 2021-09-15. High interaction valency ensures cohesion and persistence of a microtubule +TIP body at the plus-end of a single specialized microtubule in yeast. https://doi.org/10.1101/2021.09.13.460064

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