| Project/Area Number |
23370020
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plant molecular biology/Plant physiology
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| Research Institution | Nagoya University |
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Principal Investigator |
FUJITA Yuichi 名古屋大学, 生命農学研究科, 准教授 (80222264)
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| Co-Investigator(Kenkyū-buntansha) |
ITOH Shigeru 名古屋大学, 遺伝子実験施設, 名誉教授 (40108634)
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| Co-Investigator(Renkei-kenkyūsha) |
TAMIAKI Hitoshi 立命館大学, 薬学部, 教授 (00192641)
KURISU Genji 大阪大学, たんぱく質研究所, 教授 (90294131)
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| Project Period (FY) |
2011-04-01 – 2014-03-31
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| Project Status |
Completed (Fiscal Year 2013)
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| Budget Amount *help |
¥18,330,000 (Direct Cost: ¥14,100,000、Indirect Cost: ¥4,230,000)
Fiscal Year 2013: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000)
Fiscal Year 2012: ¥7,020,000 (Direct Cost: ¥5,400,000、Indirect Cost: ¥1,620,000)
Fiscal Year 2011: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000)
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| Keywords | ラジカル酵素 / 鉄硫黄クラスター / クロロフィル生合成 / 酵素反応 / 電子伝達 / プロトン移動 / 電子スピン共鳴 / ニトロゲナーゼ |
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| Research Abstract |
In final stages of biosynthesis of Chlorophylls (Chls), dark-operative protochlorophyllide (Pchlide) oxidoreductase (DPOR), a nitrogenase-like enzyme, reduces the C17=C18 double bond of Pchlide to form chlorophyllide, the direct precursor of Chl a. Crystallographic structure of DPOR suggested that the spatial arrangement of the proton donors determines the stereospecificity of the Pchlide reduction. In this study, reaction intermediates were trapped by blocking the proton transfer and they were detected by absorption and electron spin resonance spectroscopies. We proposed that the DPOR reaction consists of 1) generation of a Pchlide anion radical by a single electron transfer reaction from a [4Fe-4S]-cluster to Pchlide, 2) a second Pchlide neutral radical is formed by a single proton transfer, 3) a second electron transfer eliminates the Pchlide radical, and 4) a second proton transfer completes the reaction. DPOR is a unique radical enzyme with a structure common to nitrogenase.
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