Structural investigations on the ATP-synthase from chloroplasts

来自叶绿体的f型atp合成酶将atp合成/水解偶联到跨膜质子运输。atp合酶由两个结构不同的单元组成，一个是膜内的Fo，它携带质子易位机制，另一个是外源性的F1，它容纳核苷酸结合位点。F1和Fo通过具有中心杆和外围定子的较薄连接区域连接。这种酶的工作原理是旋转机制，其中质子的传输导致Fo中环状结构的旋转，从而使中心茎共同旋转。茎的旋转引起核苷酸结合位点的构象变化，这是合成/水解所必需的。由于缺乏高分辨率的结构信息，对这一机制的详细了解受到阻碍。完整的atp合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的亚配合物上，而对Fo和外围定子的原子结构知之甚少。因此，我们的目标是使用x射线晶体学来确定叶绿体或含有部分Fo的亚复合物或外围连接器的整个atp合酶的原子结构。为了获得催化的动态图像，高分辨率的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，这些图将由电子显微镜研究得出。

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.