| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
The oxygen sensor protein FixL, which locates in the rhizobium in leguminous root nodules, senses the environmental oxygen tension and transmits the information to the nearby protein FixJ, which regulates the expression of the enzyme system for the nitrogen fixation. Therefore, the protein FixL is the key factor to connect the environment and DNA activation. Since FixL has a heme for oxygen sensing, it belongs to hemoprotein group together with hemoglobin and myoglobin.
In this project between 2000 and 2002, we elucidated (1)structure and function of heme-containing domain of FixL, (2)differences in structure and function between FixL and other hemoproteins, (3)mechanisms for intramolecular signal transmition between heme and kinase domain, (4)mode of interaction between FixL and FixJ, (S)activation mechanism of FixJ and its action on nitrogen fixation genes, by using various molecular spectroscopies, biochemical and molecular biological techniques. In the present stage, we have completed about 90 percent of this project. Remaining problem is the autoxidation phenomenon common to almost all hemoproteins including FixL. We studied the autoxidation mechanism, and proposed "active hydrogen theory" against the traditional "active oxygen theory". Now we have a controversy against one of the referees but it will fix in the near future.
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