Structural investigations on the ATP-synthase from chloroplasts

叶绿体中的F型ATP合酶将ATP合成/水解与跨膜质子运输偶联。ATP合酶由两个结构上不同的单元组成，一个是膜包埋的Fo，它携带质子转运机制，另一个是外源性F1，它容纳核苷酸结合位点。F1和F0通过具有中心柄和外围定子的较薄连接区域连接。该酶以旋转机制工作，其中质子运输引起Fo中环状结构的旋转，其共同旋转中心柄。茎的旋转诱导合成/水解所必需的核苷酸结合位点的构象变化。由于缺乏高分辨率的结构信息，对这种机制的详细了解受到阻碍。完整的ATP酶的原子结构仍然缺失，大多数高分辨率的结构信息集中在显示可溶性F1的子复合物上，而对Fo和外周定子的原子结构知之甚少。因此，它是我们的目标，以确定整个ATP合酶的叶绿体或子复合物含有部分Fo或周边连接器使用X-射线晶体学的原子结构。为了获得催化的动态图像，高分辨率结构信息将与不同构象状态的ATP合酶的低分辨率图相结合，这将来自电子显微镜研究。

The F-type ATP-synthase from chloroplasts couples ATP-synthesis/hydrolysis to a transmembrane proton transport. The ATP-synthase consists of two structurally distinct units, a membrane embedded Fo, which carries the proton translocation machinery, and an extrinsic F1, which accommodates the nucleotide binding sites. F1 and Fo are connected by a thinner connecting region with a central stalk and a peripheral stator. The enzyme works with a rotary mechanism, where proton transport causes rotation of a ring-like structure in Fo, which co-rotates the central stalk. The rotation of the stalk induces conformational changes in the nucleotide binding sites which are necessary for synthesis/hydrolysis. The detailed understanding of this mechanism is hampered by a lack of high resolution structural information. Atomic structures of complete ATP-synthases are still missing and most high resolution structural information is focussed on sub-complexes showing the soluble F1, whereas only little is known on the atomic structure of Fo and the peripheral stator. Therefore, it is our aim to determine an atomic structure of either the whole ATP-synthase from chloroplasts or sub-complexes containing parts of Fo or the peripheral connector using X-ray crystallography. To get a dynamic picture of catalysis the high resolution structural information will be combined with low resolution maps of the ATP-synthase in different conformational states, which will be derived from electron microscopic investigations.