Assembly of human ATP synthase

人 ATP 合酶的组装

• 批准号: MR/V009672/1
• 负责人: John Walker
• 金额: $ 107.24万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FV009672%2F1
• 关键词: Assembly; human; ATP; synthase

Energy from the food we ingest is broken down by oxidative processes in our bodies. The net effect is to generate potential energy in the form of a voltage across the inner membranes of the mitochondria. The mitochondria are the cellular power-houses that generate the fuel required to provide the energy for biological processes such as muscular action, thought processes and replicating DNA and proteins. The fuel is provided in the form of the molecule adenosine triphosphate, known simply as ATP. Every day, each one of us generates 50-60 kg of ATP in the mitochondria of our cells to sustain our bodily activities. The ATP is produced in the mitochondria by millions of copies of a tiny molecular machine with a rotary action known as ATP synthase. The mitochondria are surrounded by two biological membranes and the ATP synthases are embedded in the inner one, with their synthetic heads pointing towards the inside making them resemble tiny mushrooms. In the membrane embedded region of the ATP synthase, the voltage across the membrane makes a rotor turn at about 100-200 rotations every second. The rotor is attached to a robust stalk which penetrates into the catalytic head, and the rotation of the stalk recombines spent fuel elements to form new ATP which is released into the mitochondria. The head and a static structure are joined by a second protein linkage called the peripheral stalk, which is required to prevent the head and rotor turning together. From the mitochondrion, the ATP is distributed around the cell by transport processes and, after release of energy from ATP, the spent fuel in the form of the molecules adenosine diphosphate (ADP) and inorganic phosphate is brought back to the mitochondria to be recombined into new ATP molecules. The rotary machines are both complex and fragile. They need to be put together when the mitochondria are made, and replaced when they break down. They are made from 29 proteins of 18 different kinds. The instructions for making all but two of these proteins resides in the cellular nucleus, and these proteins are made outside the mitochondrion and then imported to the inside. Here they are assembled into the ATP synthases together with the two other proteins that are made inside the mitochondrion with instructions from a small DNA molecule that resides there. We are studying how these complicated machines are assembled. We have discovered that the proteins are first assembled into specific preformed modules and then joined together to make the complete machine, rather like the simpler components of a car are assembled into the engine, gear-box and other modules before being made into the complete vehicle. The ATP synthase modules correspond to the catalytic head, the membrane part of the rotor and the peripheral stalk. The assembly of the membrane part of the rotor and that catalytic head require other proteins that are not part of the finished machines to help in the assembly process. We are studying the properties of these factors, partly because human mutations in at least two of them leads to disease. Finally, the completed machines pair up, linked together in their membrane domains, with the heads at about 90 degrees to each other, and the pairs associate into long rows and help give the inner membranes of the mitochondria their characteristic invaginated appearance. We want to know more about how this happens.

我们摄入的食物中的能量会被体内的氧化过程分解。净效应是在线粒体内膜上产生电压形式的势能。线粒体是细胞的发电厂，它产生所需的燃料，为肌肉活动、思维过程以及复制 DNA 和蛋白质等生物过程提供能量。燃料以三磷酸腺苷分子（简称 ATP​​）的形式提供。每天，我们每个人都会在细胞线粒体中产生 50-60 公斤 ATP，以维持我们的身体活动。 ATP 是在线粒体中由数百万个具有旋转作用（称为 ATP 合酶）的微小分子机器产生的。线粒体被两层生物膜包围，ATP合酶嵌入内部一层，它们的合成头指向内部，使它们看起来像小蘑菇。在 ATP 合酶的膜嵌入区域中，膜上的电压使转子每秒转动约 100-200 转。转子连接到一根插入催化头的坚固杆上，杆的旋转将用过的燃料元素重新组合，形成新的 ATP，然后释放到线粒体中。头部和静态结构通过称为外围茎的第二种蛋白质连接连接，这是防止头部和转子一起转动所必需的。来自线粒体的 ATP 通过运输过程分布在细胞周围，并且在 ATP 释放能量后，二磷酸腺苷 (ADP) 和无机磷酸盐分子形式的废燃料被带回线粒体，重新组合成新的 ATP 分子。旋转机器既复杂又脆弱。当线粒体形成时，它们需要被组合在一起，当线粒体分解时，它们需要被替换。它们由 18 种不同的 29 种蛋白质组成。除两种蛋白质外，制造所有这些蛋白质的指令都位于细胞核中，这些蛋白质是在线粒体外部制造的，然后输入到内部。在这里，它们与线粒体内产生的另外两种蛋白质一起组装成 ATP 合酶，并按照线粒体中的小 DNA 分子的指令进行组装。我们正在研究这些复杂的机器是如何组装的。我们发现，蛋白质首先被组装成特定的预制模块，然后连接在一起形成完整的机器，就像汽车的更简单的部件在制成完整的车辆之前被组装成发动机、变速箱和其他模块一样。 ATP合酶模块对应于催化头、转子的膜部分和外围柄。转子的膜部分和催化头的组装需要不属于成品机器的其他蛋白质来帮助组装过程。我们正在研究这些因素的特性，部分原因是其中至少两个因素的人类突变会导致疾病。最后，完成的机器配对，在膜域中连接在一起，头部彼此成约 90 度，并且成对的机器连接成长排，帮助线粒体内膜呈现出特有的内陷外观。我们想更多地了解这是如何发生的。