| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
In order to investigate whether taurine functions as a compatible solute for stress tolerance of plants, we expressed taurine synthetic enzyme genes in yeast used as a model organism. At first, isolation of cDNA clones for genes encoding enzymes involved in biosynthesis of taurine was attempted. Two kinds of cDNA clones corresponding to genes encoding cysteine dioxygenase (CDO1 and CDO2 and a cDNA clone for cysteine sulfinate decarboxylase (CSD) were isolated from Cyprinus carpio. Deduced amino acid sequences of the two CDOs showed high similarity to those of CDOs from other organisms. Deduced amino acid sequence of CSD also showed high similarity to those of CSDs from other organisms. The coding regions of cdol, cdo2, and csd were subcloned into an expression vector, pESC-TRP, for Saccharomyces cerevisiae. Furthermore, to enhance the efficiency of synthesis of taurine in S. cerevisiae, expression of a CDO-CSD fusion protein was also done. Expression of the CDO and CSD proteins, or CDO-CSD fusion protein was confirmed by Western blot analysis. HPLC analysis showed that the expression of the proteins led to accumulation of hypotaurine at 41 μmol/g dry weight and that of taurine at 25 μmol/g dry weight. Furthermore, transformed yeast showed the improvement of oxidative stress tolerance, but not freezing tolerance. Then, the genes encoding CDO-CSD fusion protein was introduced into an expression vector, pBE2113, for plants.
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