?-Tubulin complex in Trypanosoma brucei: molecular composition, subunit interdependence and requirement for axonemal central pair protein assembly.

ABSTRACT: ?-Tubulin complex constitutes a key component of the microtubule-organizing center and nucleates microtubule assembly. This complex differs in complexity in different organisms: the budding yeast contains the ?-tubulin small complex (?TuSC) composed of ?-tubulin, gamma-tubulin complex protein (GCP)2 and GCP3, whereas animals contain the ?-tubulin ring complex (?TuRC) composed of ?TuSC and three additional proteins, GCP4, GCP5 and GCP6. In Trypanosoma brucei, the composition of the ?-tubulin complex remains elusive, and it is not known whether it also regulates assembly of the subpellicular microtubules and the spindle microtubules. Here we report that the ?-tubulin complex in T.?brucei is composed of ?-tubulin and three GCP proteins, GCP2-GCP4, and is primarily localized in the basal body throughout the cell cycle. Depletion of GCP2 and GCP3, but not GCP4, disrupted the axonemal central pair microtubules, but not the subpellicular microtubules and the spindle microtubules. Furthermore, we showed that the ?TuSC is required for assembly of two central pair proteins and that ?TuSC subunits are mutually required for stability. Together, these results identified an unusual ?-tubulin complex in T.?brucei, uncovered an essential role of ?TuSC in central pair protein assembly, and demonstrated the interdependence of individual ?TuSC components for maintaining a stable complex.

SUBMITTER: Zhou Q 

PROVIDER: S-EPMC4636443 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature