Molecular machinery regulating energy and metabolic networks in plant cells

调节植物细胞能量和代谢网络的分子机器

基本信息

批准号：
15GS0320
负责人：
HASE Toshiharu
金额：
$ 209.83万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Creative Scientific Research
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2007
项目状态：
已结题

项目摘要

Plants synthesize various biomaterials through the reductive assimilation of inorganic carbon and nitrogen compounds. In these metabolic processes, an electron carrier protein, ferredoxin (Fd) plays a main role as an electron donor in the networks of energy and metabolic pathways. This study focused structures and functions of molecular machineries in these networks. Three projects were planed; 1) elucidation-of redox cascades via Fd in chloroplasts and nonphotosynthetic plastids, 2) determination of the structures of electron transfer complexes between Fd and partner enzymes, and 3) study of regulatory basis of these network in light of the electron partitioning.Following results have been obtained. 1) Structures of leaf-type Fd, FNR and their complex, root-type Fd, FNR and their complex, SiR, and complex of Fd and SiR were determined by x-ray crystallographic analysis. In these 3 complexes, different molecular surface of Fd were contributed as the area for the interaction of each partner enzyme. The distances between redox centers in the complexes are different, but a through-space electron transfer seems to operate in both cases. 2) Protein-protein interaction in the complexes of Fd: FNR and Fd: SiR were elucidated by NMR analysis and the molecular recognition in solution state agrees well with that in crystal. 3) Knock-out mutant of FNR and knock-down mutant of Fd in Arabidopsis were selected. The resulting mutants, in which amounts of FNR and Fd and sub-chloroplast distribution of FNR were changed, showed an alteration in the electron partitioning between carbon and nitrogen assimilation, decrease in non-cyclic electron transfer level, and increase in reducing state level of photosystem II. These phenomena indicated the absolute amount of Fd and FNR, and their ratio are crucial factors for determination of electron availability and partitioning in chloroplasts.

植物通过还原无机碳和氮化合物的还原性同化来合成各种生物材料。在这些代谢过程中，电子载体蛋白铁蛋白（FD）在能量和代谢途径网络中作为电子供体起主要作用。这项研究集中于这些网络中分子机械的结构和功能。计划了三个项目； 1）通过FD在叶绿体和非晶状体质体中通过FD阐明氧化还原级联反应，2）确定FD和伴侣酶之间电子转移复合物的结构，以及3）研究基于电子隔离结果的网络基础。 1）通过X射线晶体学分析确定了叶型FD，FNR及其复合物，根类FD，FNR及其复合物，SIR和SIR复合物的结构。在这3个复合物中，将不同的FD分子表面作为每个伴侣酶相互作用的面积。复合物中的氧化还原中心之间的距离不同，但是在两种情况下，贯穿空间的电子转移似乎都起作用。 2）通过NMR分析阐明了FD：FNR和FD：SIR的蛋白质 - 蛋白质相互作用，溶液状态中的分子识别与晶体中的分子识别非常吻合。 3）选择了FNR的敲除突变体和拟南芥中FD的敲除突变体。所得的突变体发生了FNR的FNR和FD量以及FNR的亚氯植物分布，显示了碳和氮同化之间的电子分配发生了变化，非环电子电子转移水平的降低以及降低的光系统状态II的降低。这些现象表明FD和FNR的绝对量，它们的比率是确定叶绿体中电子可用性和分配的关键因素。