Subunit Interactions in the Chloroplast ATP Synthase

在光合作用中，光能被转化为化学能，其中大部分以可以用作食物的形式存在。由腺苷5ı-diphosphate和无机磷酸盐合成腺苷5ı-triphosphate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被称为ATP合酶的非凡的酶机器催化的。这种酶由9种不同的蛋白质和总共约20个多肽链组成。利用生物化学和生物物理方法以及定点诱变，将探讨叶绿体ATP合酶中蛋白质的功能。例如，特定蛋白质在催化和调节活性中的作用将被进一步定义。深入了解ATP合酶的结构也将获得。ATP合酶非常稳定，尽管它很复杂。非共价蛋白-蛋白相互作用是这种稳定性的原因。哪些蛋白质之间的相互作用对酶的稳定贡献最大将被研究。这项工作的意义不仅在于进一步了解光合作用。一些细菌的线粒体和质膜含有一种类似于叶绿体酶的ATP合成酶。因此，叶绿体ATP合酶的研究与氧化磷酸化的研究直接相关。叶绿体ATP合酶稳定性的研究也具有重要意义，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lifeıs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.