Characteristics of novel protein interactions of gamma-tubulin and their roles with microtubules and in cell division

Spatial and temporal regulation of microtubule nucleation and dynamics is required for formation of specific microtubular arrays that react to internal and external signals and change accordingly. Microtubules are nucleated from microtubule-organizing centres such as centrosomes in animal cells or spindle pole bodies in fungi. All higher plants lack centrosomes and thus present a model for study of acentrosomal cell division and microtubule nucleation and organization. γ-Tubulin is a conserved protein from tubulin superfamily with a central role in microtubule nucleation. It also regulates microtubule dynamics and organization including mitotic spindle positioning. Moreover, γ-tubulin functions in cell cycle regulation, checkpoints control, regulation of transcription, and coordination of late mitotic events. We aimed to characterize protein interactions of γ-tubulin and their functions in Arabidopsis. We identified Arabidopsis homologue of putative centrososomal protein RanBPM. Our data showed that AtRanBPM is a member of CTLH complexes. Our finding of CTLH complexes in plants confirmed their conservation in eukaryotic cells. We found that NITRILASE1 is a cell cycle regulator in Arabidopsis that is important for maintenance of genome stability and proper cell division. We studied a role of AtTPX2,..