Temperature, photosynthesis, and rubisco

自工业革命以来大气二氧化碳水平的上升与上个世纪的强烈气候变暖有关。了解光合作用对温度和其他环境因素变化的反应是预测自然植物群落和农业物种对全球变化反应的重要组成部分。光合作用通常有一个最适温度，可以根据特定物种及其新陈代谢的不同而广义或狭义地定义；光合作用的下降明显高于或低于这个最适温度。目前，关于导致光合作用二氧化碳固定率低于最适温度的因素，文献中存在相当大的争论。这里提出的研究将使用减少了Rubisco数量的转基因植物来解决这些问题。Rubisco是主要的二氧化碳固定酶。此外，这项研究还将探索光合作用对温度的适应反应，特别是那些影响二氧化碳受体分子再生的反应。从长远来看，我的研究将集中在Rubisco本身。Rubisco是地球上含量最丰富的蛋白质，但它的动力学性质相对较差，其功能的几个方面尚不清楚。我将与海外合作者一起，表征这种酶在黄花属内的生化参数，以检验这些特征的进化。*我们将结合对该酶的结构研究，包括蛋白质测序和X射线结晶学，以澄清Rubisco结构和功能之间的联系。

The rise in levels of atmospheric CO2 since the industrial revolution has been linked to strong climate warming in the last century.  Understanding the response of photosynthesis to variation in temperature and other environmental factors is a vital component of predicting the response of natural plant communities and agricultural species to global change.  Photosynthesis typically has a thermal optimum that can be broadly or narrowly defined depending on the particular species and its metabolism; photosynthesis declines appreciably above or below this optimum.  At present there is considerable debate in the literature regarding the factors that lead to the reduction in photosynthetic CO2 fixation above the thermal optimum.  The research proposed here will address these issues using transgenic plants that have reduced amounts of Rubisco, the principle CO2-fixing enzyme.  In addition, this research will explore the acclimation responses of photosynthesis to temperature, in particular those reactions that effect the regeneration of the CO2-acceptor molecules.  In the long term my research will focus on Rubisco itself.  Rubisco is the most abundant protein on Earth, but it has relatively poor kinetic qualities and several aspects of its function remain unclear.  In conjunction with overseas collaborators, I will characterise the biochemical parameters of this enzyme within the genus Flaveria to examine the evolution of these traits.  We will incorporate structural studies of the enzyme, including protein sequencing and x-ray crystallography, in order to clarify the links between the structure and function of Rubisco.