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.

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 这个项目涉及活细胞中的一个基本问题，膜形态发生。然而，该项目将重点放在一种非医学有机体--光合细菌上；它们的发色团提供了膜形态发生的一个典型例子。紫色光合菌的发色团似乎是由膜中光合蛋白的聚集和自组织形成的[1，2]。生色团的整体形状因物种和蛋白质组成的不同而不同，并取决于捕光复合体II(LH2)和捕光复合体I(LH1)的排列。LH2和二聚体LH1的组合形成球形色团，LH2本身的存在也是如此[3，4]。层状色团通常包含LH2和单体LH1[5，6]。我们感兴趣的是探索LH2是如何产生曲率的，无论是它自己还是与LH1结合在一起。我们以前发现，在模拟中，六角填充的LH2平衡形成一个弯曲的蛋白质斑块[7]。弯曲的程度取决于蛋白质在膜中堆积的紧密程度，以及LH2晶体结构或模型来自哪些细菌物种。所有的LH2系统都形成了曲率，甚至那些来自具有自然片层的物种的系统也是如此，即平坦的色团，这表明通过聚集形成球状曲率对所有LH2都是共同的[7]。我们最近的工作旨在扩大我们对LH2-LH2相互作用产生曲率的机制的理解。似乎由于空间相互作用和蛋白质细胞质一侧保守带电残基的静电斥力的共同作用，聚集体中的每个LH2都倾向于与相邻的LH2倾斜。用中性残基取代这些残基的修饰后的LH2产生的曲率比未修饰的对应物小。我们还发现，在相同的模拟时间尺度上，围绕着LH1单体的LH2几乎没有产生曲率。这似乎部分是由于带电残基在LH1和LH2上的放置不匹配，并与实验观察一致，即平板色团主要包含LH2和LH1单体的均匀混合物。这些结果已提交发表。明年，我们计划扩大我们的模拟范围，以包括更多的LH2(因为实验表明更高浓度的LH2会导致更大的曲率[4])，并覆盖在色团的AFM图像中看到的更大区域的LH1/LH2混合区域，以更好地了解这两种蛋白质之间的相互作用。球形红杆菌光合膜的组装和组织。照相。光生物醇。科学，4：10231027,2005年。[2]R.N.Frese，J.C.P‘amies，J.D.Olsen，S.Bahatyrova，C.D.van der Wej-de Wit，T.J.Aartsma，C.Otto，C.N.Hunter，D.Frenkel，和R.van Grondelle。蛋白质形状和拥挤驱动生物膜中结构域的形成和曲率。[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，C.N.Hunter。光合膜的天然结构。《自然》，430：10581062,2004年。[4]J.N.斯特吉斯和R.A.尼德曼。不同水平的B800-B850捕光复合体对球形红杆菌胞质内膜发育的影响拱门。微生物学，165：235242,1996年。[5]S.Scheuring，D.Levy，和J.-L.Rigaud。用原子力显微镜观察光合作用细菌膜的组成及其原位组织。生物群落。《学报》，1712：109127,2005.[6]R.P.Gon？calves，A.Bernadac，J.N.斯特吉斯，S.褐孔藻光合器的构筑。J·斯特鲁特。生物，152：221228,2005.[7]D.钱德勒，J.新，C.B.哈里森，J.甘巴特，K.舒尔滕.生色团中光合蛋白的内禀曲率特性。生物群落。J.，95：28222836,2008。