Target molecule recognition and redox regulation by the chloroplast thioredoxin

A.硫氧还蛋白与其靶标的相互作用我们首先研究了植物胞质硫氧还蛋白(TRX-H1)与胞质苹果酸脱氢酶之间的相互作用，并成功地揭示了该苹果酸脱氢酶是新发现的TRX-靶蛋白。然后，我们研究了来自光合作用细菌和蓝藻的硫氧还蛋白的对应蛋白质，以揭示硫氧还蛋白作用的多样性。此外，我们还阐明了铁氧还蛋白依赖的硫氧还蛋白还原酶途径和NADPH依赖的硫氧还蛋白还原酶途径这两条氧化还原等量供应途径在聚球藻中的作用差异。硫氧还蛋白与其靶标之间蛋白质-蛋白质相互作用的结构分析。最有趣的问题之一是为什么硫氧还蛋白能识别各种蛋白质，这些蛋白质包含分子表面氧化还原敏感的二硫键，作为它们的靶标。为了回答这个问题，我们试图用X射线结晶学来解决硫氧还蛋白-靶蛋白共复合物的晶体结构。虽然我们试图在不同的化学条件下有效地获得共络合物，但在研究期间未能建立合适的实验条件来获得复杂的蛋白质，也无法解决任何可能参与相互作用的氨基酸残基的重要结构。

A. Interaction between thioredoxins and their targetsWe first studied the interaction between the plant cytosolic thioredoxin (Trx-hl) and the cytosolic malate dehydrogenase and successfully revealed that this malate dehydrogenase is the newly identified Trx-target protein. We then studied the counterpart proteins of thioredoxins from photosynthetic bacteria and cyanobacteria to reveal the multiplicity of the role of thioredoxins. In addition, we clarified the difference of the roles of two redox-equivalent supply pathways, ferredoxin-dependent thioredoxin reductase pathway and NADPH dependent thioredoxin reductase pathway in the cyanobacteria Synechocystis sp. PCC6803.B. Structural analysis of the protein-protein interaction between thioredoxins and their targets.One of the most interesting questions are why thioredoxins can recognize various proteins, which contains the redox sensitive disulfide bond on the molecular surface, as their target. In order to answer this query, we tried to solve the crystal structures of the thioredoxin-target protein cocomplex using X-ray crystallography. Although we have tried to efficiently obtain the co-complexexes under the various chemical conditions, we failed to set up the suitable experimental conditions to obtain the complex proteins during the research term and could not solve any structures which should be important to know the amino acid residues which may involve into the interaction.