Poster: Education
Abs #
27: Functional analysis of TONSOKU suggests its role in the cell cycle
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Presenter: |
Suzuki, Takamasa , i992009d@media.nagoya-u.ac.jp |
Authors | Suzuki, Takamasa (A) Nakajima, Sakiko (A) Hirano, Makiko N (A) Matsuoka, Ken (B) DemuraTaku, (B) Fukuda, Hiroo (B) Morikami, Atsushi (C) Nakamura, Kenzo (A) | | Affiliations: |
(A): Graduate School of Bioagricultural Sciences, Nagoya University
(B): RIKEN Plant Science Center
(C): Collage of Bioscience and Biotechnology, Chubu University
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tonsoku (tsk) mutants of Arabidopsis thaliana with fasciated stems and shorter roots often shows abnormal direction of cell division in the shoot and root apical meristems. TSK protein contains leucine-rich repeats and LGN repeats both of which are implicated to be involved in the protein-protein interaction. Yeast two-hybrid screen for proteins interacting with TSK using the LGN repeats of TSK as a bait resulted in the isolation of several candidate clones. Two of them, POT1 and POT3, were further characterized. POT1 was a novel protein with 10-times repeats of 40 amino acid residues, and POT3 was a protein with high similarities to a tobacco DNA-binding protein implicated to be involved in cell proliferation after Agrobacterium-infection. In vitro co-immunoprecipitation assay and further analyses using yeast two-hybrid method revealed that these proteins interact with different domains of TSK. A TSK-GFP fusion protein expressed in tobacco BY-2 cells was localized in nucleus, although it was not detected in nucleolus. In BY-2 cells synchronized for the cell cycle, TSK-GFP was found to move into each daughter cells proceeding the distribution of chromatin. A tobacco homolog of TSK, NtTSK, showed high sequence identities with TSK in several regions including LGN repeats. Expression of NtTSK showed cell cycle-dependent oscillation and the highest level of its expression was observed in the early S phase. Suppression of expression of NtTSK by dexamethasone-induced RNAi seemed to affect the progression of the cell-cycle. From these results, it was suggested that TSK forms a nuclear-localized protein complex with several other proteins and this complex plays a role in the regulation of progression of the cell cycle.
