Subunit Interactions in the Chloroplast ATP Synthase

9723945麦卡蒂在光合作用中将光能转化为化学能，其中大部分以可用作食物的形式存在。由腺苷5-ı-二磷酸和无机磷合成腺苷-5-ı-三磷酸是光合作用中必不可少的反应。这种需要能量的反应是由一种非凡的酶机器催化的，这种机器被称为ATP合成酶。这种酶是由9种不同的蛋白质和总共约20个多肽链组成的聚集体。利用生化和生物物理方法以及定点突变，将探索叶绿体ATP合成酶中蛋白质的功能。例如，特定蛋白质在催化和活性调节中的参与将得到进一步的定义。对三磷酸腺苷合成酶的结构也将有深入的了解。尽管ATP合成酶很复杂，但它是非常稳定的。蛋白质之间的非共价相互作用是这种稳定性的原因。将研究哪些蛋白质之间的相互作用对酶的稳定做出了最大贡献。这项拟议的工作不仅对光合作用有进一步的理解，而且具有重要意义。一些细菌的线粒体和质膜含有一种类似于叶绿体酶的三磷酸腺苷合成酶。因此，对叶绿体ATP合成酶的研究与氧化磷酸化的研究是直接相关的。研究叶绿体ATP合成酶的稳定性也具有重要意义，因为它是研究蛋白质-蛋白质相互作用的一个很好的模型系统。蛋白质之间的相互作用是所有生命ıS过程的基础。

9723945 McCarty In photosynthesis light energy is converted to chemical energy, much of it in the form that can be used as food. The synthesis of adenosine 5ı-triphosphate from adenosine 5ı-diphosphate and inorganic phosphate is an essential reaction in photosynthesis. This energy requiring reaction is catalyzed by a remarkable enzymatic machine, known as the ATP synthase. This enzyme is an aggregate of nine different proteins and a total of about 20 polypeptide chains. Using biochemical and biophysical approaches as well as site-directed mutagenesis, the functions of the proteins in the chloroplast ATP synthase will be probed. For example, the involvement of specific proteins in catalysis and in regulation of activity will be further defined. Insights into the structure of the ATP synthase will also be obtained. The ATP synthase is very stable, despite its complexity. Noncovalent protein-protein interactions are responsible for this stability. Which interactions among the proteins contribute most to the stabilization of the enzyme will be studied. The proposed work has significance beyond reaching a further understanding of photosynthesis. Mitochondria and the plasma membrane of some bacteria contain an ATP synthase that is similar to the chloroplast enzyme. Thus, studies on the chloroplast ATP synthase are directly relevant to those on oxidative phosphorylation. The investigation of the stability of the chloroplast ATP synthase also assumes importance in that it is an excellent model system for the study of protein-protein interactions. Protein-protein interactions are fundamental to all of lifeıs processes.