CELLULAR ARCHITECTURE II: PHOTOSYNTHETIC CORE COMPLEX

细胞架构 II：光合成核心复合物

• 批准号: 7955617
• 负责人: JEN HSIN
• 金额: $ 5.75万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7955617
• 关键词: Architecture; Bacteria; Bibliography; Bioinformatics; Cells; Chromatophore; Complex; Computer Retrieval of Information on Scientific Projects Database; Electron Microscopy; Electrons; Funding; Grant; Institution; Maps; Medical; Membrane; Methods; Modeling; Molecular; Morphogenesis; Organism; Property; Proteins; Proteobacteria; Research; Research Personnel; Resolution; Resources; Rhodobacter sphaeroides; Shapes; Source; Structure; Tubular formation; Uncertainty; United States National Institutes of Health; Vesicle; base; density; dimer; flexibility; improved; molecular dynamics; simulation; two-dimensional

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The photosynthetic proteins in purple bacteria not only carry out the intricate processof energy conversion, but are also responsible for organizing the membrane intodistinct cellular compartments with well-defined shapes. Indeed, electron tomographyand electron microscopy have discovered that the photosynthetic proteins inpurple bacteria aggregate in the membrane to form independent photosyntheticunits with different shapes and sizes depending on species and protein composition.Among the membrane-bending photosynthetic proteins, the Rhodobactersphaeroides core complex is the only one thought to induce cylindrical curvature andbuild tubular vesicles in bacterial cells. However, lack of high resolution structuresfor the core complex has rendered it difficult to investigate its membrane-bendingmechanism. This project deals with a non-medical photosynthetic organism becauseof the principle importance of membrane morphogenesis for the cells of allorganisms.Previously, we constructed a rudimentary all-atom model for the Rhodobactersphaeroides core complex [1] based on the then-available two-dimensional electronmicroscope projection map [2], and showed that the core complex, a dimeric construct,bends slightly and produces curvature in the surrounding membrane. Althoughthese simulations explain the mechanism of core complex-induced membranecurvature, the curvature observed was insufficient to reproduce the known size ofthe core complex tubular vesicles due to uncertainty of the core complex structure.Recently, a three-dimensional electron miscroscope map became available,displaying a highly-bent core complex [3] and provided an opportunity to furtherfine-tune our understanding of the core complex structure. Combining the earlierall-atom model with the new three-dimensional density map [3] using the moleculardynamics flexible fitting method [4], an improved core complex model was generated[5, 6]. The large bending of the complex induced a high local curvature in themembrane, which agreed well with the size of the core complex tubular vesicles [5].Furthermore, the simulations demonstrated how the local curvature properties ofthe RC-LH1-PufX dimer propagate to form the observed long-range organizationof the Rhodobacter sphaeroides tubular vesicles [5].BIBLIOGRAPHY[1] D. Chandler, J. Hsin, C. B. Harrison, J. Gumbart, and K. Schulten. Intrinsic curvatureproperties of photosynthetic proteins in chromatophores. Biophys. J., 95:28222836,2008.[2] P. Qian, C. N. Hunter, and P. A. Bullough. The 8.5 ¿A projection structure of the coreRC-LH1-PufX dimer of Rhodobacter sphaeroides. J. Mol. Biol., 349:948960, 2005.[3] P. Qian, P. A. Bullough, and C. N. Hunter. Three-dimensional reconstructionof a membrane-bending complex: The RC-LH1-PufX core dimer of Rhodobactersphaeroides. J. Biol. Chem., 283:1400214011, 2008.[4] L. G. Trabuco, E. Villa, K. Mitra, J. Frank, and K. Schulten. Flexible fitting ofatomic structures into electron microscopy maps using molecular dynamics. Structure,16:673683, 2008. PMCID: PMC2430731.[5] J. Hsin, J. Gumbart, L. G. Trabuco, E. Villa, P. Qian, C. N. Hunter, and K. Schulten.Protein-induced membrane curvature investigated through molecular dynamicsflexible fitting. Biophys. J., 2009. In press.[6] M. K. Sener, J. Hsin, L. G. Trabuco, E. Villa, P. Qian, C. N. Hunter, and K. Schulten.Structural model and excitonic properties of the dimeric RC-LH1-PufX complex fromRhodobacter sphaeroides. Chem. Phys., 357:188197, 2009.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 紫色细菌中的光合作用蛋白质不仅执行复杂的能量转换过程，而且还负责将膜组织成具有明确形状的不同细胞区室。事实上，电子断层扫描和电子显微镜已经发现，紫色细菌的光合蛋白在细胞膜上聚集，形成独立的光合单位，这些光合单位的形状和大小取决于细菌的种类和蛋白质组成。在弯曲膜的光合蛋白中，球形红球藻核心复合物是唯一一个被认为能诱导细菌细胞的圆柱形弯曲和形成管状囊泡的蛋白。然而，由于缺乏高分辨率的核心复合物的结构，使得难以研究其膜弯曲机制。由于膜形态发生对所有生物细胞的重要性，本项目涉及非医学光合生物。以前，我们基于当时可用的二维电子显微镜投影图[2]构建了球形红杜鹃核心复合物的基本全原子模型[1]，并表明核心复合物，一个二聚体结构，轻微弯曲并在周围膜中产生曲率。尽管这些模拟解释了核心复合物诱导膜弯曲的机制，但由于核心复合物结构的不确定性，观察到的曲率不足以再现已知的核心复合物管状囊泡的大小。最近，三维电子显微镜图可用，显示高度弯曲的核心复合物[3]，并提供了进一步微调我们对核心复合物结构的理解的机会。使用分子动力学灵活拟合方法[4]将早期的全原子模型与新的三维密度图[3]结合起来，生成了改进的核心复合物模型[5，6]。复合物的大弯曲在膜中诱导了高的局部曲率，这与核心复合物管状囊泡的尺寸非常一致[5]。此外，模拟显示了RC-LH 1-PufX二聚体的局部曲率特性如何传播以形成所观察到的球形红细菌管状囊泡的长程组织[5]。钱德勒、辛俊、C. B。Harrison，J. Gumbart，and K.舒尔滕色素细胞光合作用蛋白质的内在曲率特性。Biophys. J.，九十五：二八二二2836,2008. [2]P. Qian，C. N.亨特和助理布洛球形红细菌核心RC-LH 1-PufX二聚体的8.5 <$A投影结构。J. Mol.生物学：三百四十九：九百四十八960，2005年。[3]P. Qian，P. A. Bullough和C. N.猎人膜弯曲复合物的三维重建：球形红杜鹃的RC-LH 1-PufX核心二聚体。J. Biol. Chem.，283：1400214011，2008年。[4]L. G. Trabuco，E.维拉湾Mitra，J. Frank，and K.舒尔滕用分子动力学将原子结构灵活地拟合到电子显微镜图中。结构，16：673683，2008年。PMCID：PMC2430731。[5]J. Hsin，J. Gumbart，L. G. Trabuco，E. Villa，P. Qian，C. N. Hunter和K.通过分子动力学柔性拟合研究蛋白质诱导的膜曲率。Biophys. J.，2009.在出版社。[6]M. K. Sener，J. Hsin，L. G. Trabuco，E. Villa，P. Qian，C. N. Hunter和K. Schulten. Rhodobacter sphaeroides的二聚RC-LH 1-PufX复合物的结构模型和激子性质。化学物理学，三五七：一八八197，2009年。