Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Japan.
Photosynth Res. 2010 Jun;104(2-3):221-31. doi: 10.1007/s11120-009-9523-2. Epub 2010 Jan 9.
Green sulfur photosynthetic bacteria optimize their antennas, chlorosomes, especially for harvesting weak light by organizing bacteriochlorophyll (BChl) assembly without any support of proteins. As it is difficult to crystallize the organelles, a high-resolution structure of the light-harvesting devices in the chlorosomes has not been clarified. We have determined the structure of BChl c assembly in the intact chlorosomes from Chlorobium limicola on the basis of (13)C dipolar spin-diffusion solid-state NMR analysis of uniformly (13)C-labeled chlorosomes. About 90 intermolecular C-C distances were obtained by the simultaneous assignment of distance correlations and the structure optimization preceded by the polarization-transfer matrix analysis. An atomic structure was obtained, using these distance constraints. The determined structure of the chlorosomal BChl c assembly is built with the parallel layers of piggyback-dimers. This supramolecular structure would provide insights into the mechanism of weak-light capturing.
绿硫光合细菌通过组织细菌叶绿素（BChl）组装来优化它们的天线和菌绿体，而无需任何蛋白质的支持，从而特别适合收集弱光。由于细胞器难以结晶，因此菌绿体中光捕获装置的高分辨率结构尚未阐明。我们通过对均匀（13）C 标记的菌绿体进行（13）C 偶极自旋扩散固态 NMR 分析，确定了来自绿杆菌（Chlorobium limicola）的完整菌绿体中 BChl c 组装的结构。通过距离相关的同时分配和极化转移矩阵分析之前的结构优化，获得了约 90 个分子间 C-C 距离。使用这些距离约束，获得了原子结构。确定的菌绿体 BChl c 组装结构是由背驮式二聚体的平行层构建的。这种超分子结构将为弱光捕获机制提供深入的了解。
