Molecular characterisation of an ADP-dependent regulatory protein

植物将二氧化碳转化为糖对地球上的生命至关重要。在大多数植物中，这一过程与氧气的非生产性反应竞争。一组植物，C4植物，已经制定了一种策略来避免这种情况：这种策略允许植物在炎热、干燥和干旱的条件下生存，否则植物就不能生长。这些植物包括常见的农作物，玉米和甘蔗。目前正在进行研究，以确定是否可以将这一途径改造到其他植物中，以培育更耐寒的作物，这项研究将为这一目标提供支持。我们的研究解决了这种制造糖的替代策略的一部分是如何被控制的。特别是，我们感兴趣的是一种不寻常的蛋白质如何在黑暗中关闭这条途径。蛋白质，丙酮酸，磷酸二激酶(PPDK)调节蛋白，或简称PDRP，使另一种蛋白质PPDK失活，从而阻止植物从丙酮酸生成化合物磷酸烯醇式丙酮酸。这阻止了植物在黑暗中(当没有光通过光合作用提供能量的时候)将二氧化碳‘固定’成糖。调节蛋白PDRP可以执行这一重要功能，因为它依赖于其底物ADP的存在才能发挥作用。这是光合作用关闭的直接结果，在黑暗中积累起来。我们感兴趣的是调控蛋白如何利用这个分子来灭活PPDK的细节。我们将开发新的方法来研究这一过程，并模拟目标，这将有助于我们进一步揭开它发生的确切方式。靶蛋白失活是因为磷酸基团从底物ADP转移到蛋白上，从而阻断了执行其正常功能所需的部分PPDK。值得注意的是，使用这种特殊的分子，腺嘌呤二磷酸(ADP)来执行这一反应是非常不寻常的，通常使用三磷酸腺苷(ATP)来代替。

Conversion of carbon dioxide to sugars by plants is essential to life on earth. In the majority of plants this process competes with non-productive reaction with oxygen. One group of plants, the C4 plants, have developed a strategy to avoid this: this strategy allows the plants to survive in hot, dry and arid conditions which would not otherwise be viable for plant growth. These plants include the common crop plants, maize and sugarcane. Research is presently underway to determine if this pathway can be engineered into other plants to generate hardier crop plants and this research will feed into this objective. Our research addresses how one part of this alternative strategy of making sugars is controlled. In particular, we are interested in how an unusual protein acts to switch off the pathway in the dark. The protein, pyruvate,orthophosphate dikinase (PPDK) regulatory protein, or PDRP for short, inactivates another protein, PPDK, thereby preventing the plant from making the compound phosphoenolpyruvate from pyruvate. This prevents the plant from 'fixing' carbon dioxide into sugars in the dark (when there is no light to provide energy via photosynthesis). The regulatory protein, PDRP, can perform this vital function because it is dependent upon the presence of its substrate, ADP, for activity. This accumulates in the dark as a direct result of photosynthesis shutting down. We are interested in the details of the way in which the regulatory protein uses this molecule to inactivate PPDK. We will develop new ways to study this process and make mimics of the target which will help us further unravel the precise manner in which it occurs. The target protein is inactivated because a phosphate group is transferred from the substrate ADP to the protein, thereby blocking the part of PPDK required to perform its normal function. It is worth noting that using this particular molecule, adenine diphosphate (ADP), to perform this reaction is highly unusual, normally adenine triphosphate (ATP) is used instead.