SGD Paper 
Cuschieri L, et al. (2006) {gamma}-Tubulin Is Required for Proper Recruitment and Assembly of Kar9-Bim1 Complexes in Budding Yeast. Mol Biol Cell 17(10):4420-34
Abstract: Monitoring Editor: Kerry Bloom Microtubule +end interacting proteins (+TIPs) promote the dynamic interactions between the +ends of astral microtubules and cortical actin that are required for pre-anaphase spindle positioning. Paradoxically, +TIPs such as the EB1 ortholog Bim1 and Kar9 also associate with spindle pole bodies (SPBs), the centrosome equivalent in budding yeast. Here, we show that deletion of 4 c-terminal residues of the budding yeast gamma-tubulin Tub4 (tub4-Deltadsyl) perturbs Bim1 and Kar9 localization to SPBs and Kar9-dependant spindle positioning. Surprisingly, we find Kar9 localizes to microtubule +ends in tub4-Deltadsyl cells, but these microtubules fail to position the spindle when targeted to the bud. Using cofluorescence and coaffinity purification, we show Kar9 complexes in tub4-Deltadsyl cells contain reduced levels of Bim1. Astral microtubule dynamics are suppressed in tub4-Deltadsyl cells, but are restored by deletion of Kar9. Moreover, Myo2 and F-actin dependant dwelling of Kar9 in the bud is observed in tub4-Deltadsyl cells, suggesting defective Kar9 complexes tether microtubule +ends to the cortex. Overproduction of Bim1, but not Kar9, restores Kar9-dependent spindle positioning in the tub4-Deltadsyl mutant, reduces cortical dwelling and promotes Bim1-Kar9 interactions. We propose that SPBs, via the tail of Tub4, promote the assembly of functional +TIP complexes before their deployment to microtubule +ends.
| Status: Published | Type: Journal Article | PubMed ID: 16899509 |
Topics addressed in this paper
Number of different genes curated to this paper: 9
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