A role for the microtubule +end protein Bik1 (CLIP170) and the Rho1 GTPase in Snc1 trafficking

Nom de la revue
Journal of Cell Science
Cécile Boscheron, Fabrice Caudron, Sophie Loeillet, Charlotte Peloso, Marine Mugnier, Laetitia Kurzawa, Alain Nicolas, Eric Denarier, Laurence Aubry, Annie Andrieux

The diversity of microtubule functions is dependent on the status of tubulin C-termini. To address the physiological role of the C-terminal aromatic residue of α-tubulin, a tub1-Glu yeast strain expressing an α-tubulin devoid of its C-terminal amino-acid was used to perform a genome-wide-lethality screen. The identified synthetic lethal genes suggested links with endocytosis and related processes. In the tub1-Glu strain, the routing of the v-SNARE Snc1 was strongly impaired, with a loss of its polarized distribution in the bud and Abp1, an actin patch/endocytic marker, developed comet-tails structures. Snc1 trafficking necessitated dynamic microtubules but not dynein and kinesin motors. Interestingly, deletion of the microtubule +end protein Bik1 (CLIP170), which is preferentially recruited to the C-terminal residue of α-tubulin, similarly resulted in Snc1 trafficking defects. Finally, constitutively active Rho1 rescued both Bik1 localization at microtubule +ends in tub1-Glu strain and a correct Snc1 trafficking in a Bik1-dependent manner. Our results provide the first evidence for a role of microtubule +ends in membrane-cargo trafficking in yeast, through Rho1- and Bik1-dependent mechanisms and highlight the importance of α-tubulin last amino-acid in this process.