Abstract
tonsoku (tsk) mutants of Arabidopsis thaliana show shorter roots and fasciated stems, which is due to abnormal structure and defective function of both shoot apical meristem and root apical meristem. TSK gene, expressed primarily in the meristem, encodes a novel protein which contains LGN repeats and Leucine-Rich (LR) repeats. Since these repeats are considered to be involved in the protein-protein interaction, it is crucial to identify protein(s) that interact with TSK to clarify the cellular function of TSK. We identified several protein(s) that interact with TSK by using yeast two-hybrid screening. One of them, POT3, was homologous to tobacco NtSIP1 that interacts with 6b protein encoded by T-DNA of Agrobacterium. The interaction between TSK and POT3 occurred through specific domain of each protein. 6b protein is a transcription factor and NtSIP1 has been shown to be targeted to the nucleus. These results suggest that TSK is involved in transcription regulation.
