The microtubule polymerase Stu2 promotes oligomerization of the ?-TuSC for cytoplasmic microtubule nucleation.

ABSTRACT: Stu2/XMAP215/ZYG-9/Dis1/Alp14/Msps/ch-TOG family members in association with with ?-tubulin complexes nucleate microtubules, but we know little about the interplay of these nucleation factors. Here, we show that the budding yeast Stu2 in complex with the ?-tubulin receptor Spc72 nucleates microtubules in vitro without the small ?-tubulin complex (?-TuSC). Upon ?-TuSC addition, Stu2 facilitates Spc72-?-TuSC interaction by binding to Spc72 and ?-TuSC. Stu2 together with Spc72-?-TuSC increases microtubule nucleation in a process that is dependent on the TOG domains of Stu2. Importantly, these activities are also important for microtubule nucleation in vivo. Stu2 stabilizes Spc72-?-TuSC at the minus end of cytoplasmic microtubules (cMTs) and an in vivo assay indicates that cMT nucleation requires the TOG domains of Stu2. Upon ?-tubulin depletion, we observed efficient cMT nucleation away from the spindle pole body (SPB), which was dependent on Stu2. Thus, ?-TuSC restricts cMT assembly to the SPB whereas Stu2 nucleates cMTs together with ?-TuSC and stabilizes ?-TuSC at the cMT minus end.

SUBMITTER: Gunzelmann J 

PROVIDER: S-EPMC6158006 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature