American Society of Plant Biologists
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Poster: Environmental Stress and Adaptation to Stress

Abs # P07110: Biochemical analysis of MIZ1, an essential protein for hydrotropism in Arabidopsis thaliana

Presenter: Yamazaki, Tomokazu       Contact Presenter
AuthorsYamazaki, Tomokazu  (A)   Akie, Kobayashi  (A)   Yutaka, Miyazawa  (A)   Hideyuki, Takahashi  (A)  
Affiliations: (A): Graduate School of Life Sciences, Tohoku University

Hydrotropism is a response by which roots sense moisture gradient and induce a directional growth toward higher water potential. We have previously screened a series of Arabidopsis mutants whose hydrotropic response are impaired. Of those mutants, miz1 is defective in hydrotropic response, resulting from a point mutation at coding sequence of a gene encoding an uncharacterized protein. Any homologous gene encoding MIZ1-like protein was not found in animal and fungal genomes, but wide spread over green plant linage including Bryophyte. Deduced amino acid sequence of MIZ1 has 297 amino acid residues, and its theoretical molecular weight is 32.5 kDa. The predicted secondary structure indicated that MIZ1 contains an unstructured region in N-terminal (1-110aa), and a structured region with 9 beta-sheets and 3 alpha-helixes in C-terminal (123-297aa). In addition, hydropathy analysis indicated that MIZ1 is soluble protein. We generated a transgenic plant expressing GFP-tagged MIZ1 (MIZ1-GFP) proteins at the unstructured region in N-terminal under the native promoter of miz1 gene. Total proteins were extracted from 5-day-old seedlings of the transgenic plant, and fractionated by centrifugation and ultra-centrifugation. Immunoblot analysis showed that MIZ1-GFP was detected not only in supernatant fraction, but also in precipitation fraction by ultra-centrifugation, suggesting that MIZ1 is a soluble protein but associated with some organella membrane. We will analyze the distinct subcellular localization of MIZ1 for understanding its unknown protein function.

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