CELLULAR ARCHITECTURE III: LIGHT HARVESTING COMPLEX II

蜂窝架构 III：光采集复合体 II

• 批准号: 7955618
• 负责人: DARRELL P CHANDLER
• 金额: $ 3.83万
• 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/7955618
• 关键词: Architecture; Area; Bacteria; Bioinformatics; Biological; Cells; Charge; Chromatophore; Complex; Computer Retrieval of Information on Scientific Projects Database; Crowding; Development; Electrostatics; Funding; Grant; Greater curvature of stomach; Harvest; Image; In Situ; Institution; LHX2 gene; Life; Light; Medical; Membrane; Modeling; Nature; Organism; Proteins; Publications; Research; Research Personnel; Resources; Rhodobacter sphaeroides; Shapes; Source; Structure; System; United States National Institutes of Health; Wit; Work; interest; monomer; patched protein; photosynthetic bacteria; research study; self organization; simulation

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. This project deals with a problem of fundamental importance in living cells, membranemorphogenesis. The project focuses, however, on a non-medical organism,photosyntetic bacteria; their chromatophores offer a prime example of membranemorphogenisis. The chromatophores of purple photosynthetic bacteria appear to beformed by the aggregation and self-organization of the photosynthetic proteins inthe membrane [1, 2]. The overall shape of the chromatophore varies among speciesand with protein composition and depends on the arrangement of light-harvestingcomplex II (LH2) and light-harvesting complex I (LH1). A combination of LH2sand dimeric LH1s results in a spherical chromatophore, as does the presence ofLH2 by itself [3,4]. Lamellar chromatophores generally contain LH2s together withmonomeric LH1s [5,6]. We are interested in exploring how LH2 produces curvature,both by itself and in combination with LH1.We found previously that hexagonally-packed LH2s in simulation equilibrate toform a curved protein patch [7]. The extent of the curvature was dependent onhow closely the proteins were packed in the membrane and which bacterial speciesthe LH2 crystal structure or model was from. All of the LH2 systems formedcurvature, even those from species with naturally lamellar, i.e. flat, chromatophores,suggesting that the formation of spherical curvature via aggregation is common toall LH2s [7].Our recent work aims to expand our understanding of the mechanism by which LH2-LH2 interactions produce curvature. It appears that each LH2 in the aggregate isinclined to tilt away from its neighbors due to a combination of steric interactionsand the electrostatic repulsion of conserved charged residues on the cytoplasmic sideof the proteins. Modified LH2s in which these residues were replaced with neutralresidues produced less curvature than their unmodified counterparts. We also foundthat LH2s packed around an LH1 monomer produced almost no curvature over thesame simulation timescale of the LH2-only systems. This seems to be due in partto a mismatch in the placement of the charged residues on LH1 vs. LH2, andis consistent with the experimental observation that flat chromatophores containmostly a homogeneous mixture of LH2s and LH1 monomers. These results havebeen submitted for publication. In the next year, we plan to expand our simulationsto include more LH2s (as experiments suggest that higher concentrations of LH2lead to greater curvature [4]) and to cover larger areas of mixed LH1/LH2 regions asseen in AFM images of chromatophores to better understand the interplay betweenthe two proteins.BIBLIOGRAPHY[1] C. N. Hunter, J. D. Tucker, and R. A. Niederman. The assembly and organisation ofphotosynthetic membranes in Rhodobacter sphaeroides. Photochem. Photobiol. Sci.,4:10231027, 2005.[2] R. N. Frese, J. C. P`amies, J. D. Olsen, S. Bahatyrova, C. D. van der Weij-de Wit,T. J. Aartsma, C. Otto, C. N. Hunter, D. Frenkel, and R. van Grondelle. Proteinshape and crowding drive domain formation and curvature in biological membranes.Biophys. J., 94:640647, 2008.[3] S. Bahatyrova, R. N. Frese, C. A. Siebert, J. D. Olsen, K. O. van der Werf, R. vanGrondelle, R. A. Niederman, P. A. Bullough, C. Otto, and C. N. Hunter. The nativearchitecture of a photosynthetic membrane. Nature, 430:10581062, 2004.[4] J. N. Sturgis and R. A. Niederman. The effect of different levels of the B800-B850light-harvesting complex on intracytoplasmic membrane development in Rhodobactersphaeroides. Arch. Microbiol., 165:235242, 1996.[5] S. Scheuring, D. Levy, and J.-L. Rigaud. Watching the components of photosyntheticbacterial membranes and their in situ organisation by atomic force microscopy.Biochim. Biophys. Acta, 1712:109127, 2005.[6] R. P. Gon¿calves, A. Bernadac, J. N. Sturgis, and S. Scheuring. Architecture of thenative photosynthetic apparatus of Phaeopirillum molischianum. J. Struct. Biol.,152:221228, 2005.[7] D. Chandler, J. Hsin, C. B. Harrison, J. Gumbart, and K. Schulten. Intrinsic curvatureproperties of photosynthetic proteins in chromatophores. Biophys. J., 95:28222836,2008.

该副本是使用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这是调查员的机构。 该项目涉及在活细胞，膜形态发生的基本重要性问题。然而，该项目将重点放在一个非医学组织，即光含量细菌上。他们的色谱提供了一个膜形基因的主要例子。紫色光合物细菌的色谱物似乎是通过膜中光合成蛋白的聚集和自组织制成的[1，2]。物种和具有蛋白质组成的物种中色谱的总体形状，取决于轻度收获Complex II（LH2）和光收获复合物I（LH1）的排列。 LH2SAND二聚体LH1S的组合会导致球形色谱，而LH2本身也存在[3,4]。层状色谱通常与单体LH1一起含有LH2 [5,6]。我们有兴趣探索LH2本身并与LH1结合使用LH2如何产生曲率。我们以前在模拟中发现了六角形的LH2等于形成弯曲蛋白斑块[7]。曲率的程度取决于蛋白质在膜中堆积的程度以及LH2晶体结构或模型来自哪种细菌。所有的LH2系统都形成了具有天然层状物种的物种，即平坦的染色体，这表明通过聚集的球形曲率形成是常见的lh2s [7] [7]。我们最近的工作旨在扩大我们对LH2-LH2相互作用产生的机制的理解。看来，由于空间相互作用和蛋白质细胞质侧构成的带电残留物的静电排斥，骨料中的每个LH2都远离其邻居倾斜。改良的LH2S，其中这些残差被中额取代的LH2所产生的曲率低于其未修饰的曲率。我们还发现，LH2在LH1单体周围挤满了LH2，几乎没有在仅LH2系统的同一模拟时间范围内产生曲率。这似乎是由于在LH1与LH2上的放置在LH2上的放置方面的一部分是不匹配的，Andis与实验观察结果一致，即扁平染色体主要包含LH2S和LH1单体的均匀混合物。这些结果已提交出版。在明年，我们计划扩展模拟阶段包括更多的LH2（正如实验表明，LH2Lead浓度更高，较高的曲率[4]），并涵盖了混合LH1/LH2区域在AFM染色体图像中的较大面积，以更好地了解两种蛋白质的相互作用。杜鹃花sphaeroides中光同步膜的组装和组织。光化学。 Photobiol。 Sci。，4：1023 1027，2005。[2] R. N. Frese，J。C。P`mies，J。D。Olsen，S。Bahatyrova，C。D。van der Weij-de Wit，T。J。Aartsma，C。Otto，C。N。Hunter，D。Frenkel和R. Van Grondelle。蛋白质和拥挤的生物膜中驱动结构域的形成和曲率。 J.，94：640 647，2008。[3] S. Bahatyrova，R。N。Frese，C。A。Siebert，J。D。Olsen，K。O。van der Werf，R。VanGrondelle，R。A。A. Niederman，P。A。Bullough，C。Otto和C. N. Hunter。光合膜的本地结构。自然，430：1058 1062，2004。[4] J. N. Sturgis和R. A. Niederman。不同水平的B800-B850光收获复合物对杜鹃花杆菌内胞浆内膜发育的影响。拱。 Microbiol。，165：235 242，1996。[5] S. Scheuring，D。Levy和J.-L。 Rigaud。通过原子力显微镜观察光合作用膜的组成部分及其原位组织。Biochim。生物。 Acta，1712：109 127，2005年。[6] R. P.Gon¿Calves，A。Bernadac，J。N。Sturgis和S. Scheuring。随后的光合作用装置的结构。 J. struct。 Biol。，152：221 228，2005。[7] D. Chandler，J。Hsin，C。B。Harrison，J。Gumbart和K. Schulten。染色体中光合蛋白的固有曲率特性。生物。 J.，95：2822 2836,2008。