The effects of proton motive force on thylakoid architecture and function

质子基序力对类囊体结构和功能的影响

• 批准号: 524969795
• 负责人: Professor Dr. Benjamin Engel, Ph.D.
• 金额: --
• 依托单位: Biozentrum
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/524969795?language=en
• 关键词: effects; proton; motive; force; thylakoid

Thylakoid membranes scaffold photosynthetic complexes, which couple electron transfer to proton movement across the membrane, thereby generating the proton motive force (PMF, composed of Delta-pH and Delta-Psi) that drives the production of ATP. Thylakoid architecture is intimately linked to efficient photosynthesis. Thylakoids are flat instead of spherical, increasing the concentration of photosynthetic complexes per luminal area to drive the PMF, while providing directionality for the diffusion of the soluble electron carrier plastocyanin through the thylakoid lumen. However, thylakoid architecture is not static and responds to changes in light quality and quantity. Preliminary electron microscopy observations in cyanobacteria, green algae, and plants have shown that the thylakoid lumen swells under increased light intensity. A logical hypothesis would be that lumen acidification (Delta-pH) and ion flux-driven changes in membrane potential (Delta-Psi) may be coupled to osmotic forces that expand the lumen. However, the precise dynamics and mechanism of this architectural change remain uncharacterized. The goal of this project is to understand the mechanistic basis and physiological consequences of light-induced thylakoid swelling, and to specifically test how this swelling is modulated by different components of the PMF. This study will be enabled by our advanced cryo-electron tomography (cryo-ET) workflow, which we have developed to measure native thylakoid architecture (membrane and lumen width) with sub-nanometer precision and analyze the organization of each photosynthetic complex along these membranes. First, we aim (i) to characterize the kinetics of thylakoid swelling in green algae (Chlamydomonas reinhardtii) and cyanobacteria (Synechocystis sp. 6803) by performing a detailed cryo-ET time-series of wild-type cells after transition from darkness to different light intensities. Next, we aim (ii) to examine the contributions of Delta-pH and Delta-Psi to thylakoid lumen expansion by combining cryo-ET with small molecule ionophores and genetic perturbations of ATP synthase and KEA3 ion antiporters. In parallel, we aim (iii) to test the specific PMF contributions of cytochrome b6f to thylakoid lumen dynamics. Finally, we aim (iv) to create an integrated model of light-dependent lumen expansion by combining our cryo-ET data with functional measurements of PMF and photosynthetic function from other members of the consortium. The focus of our project is to deliver on the overall aim 3 of GoPMF (Structural dynamics of thylakoid membranes in remodeling of energy conversion systems). Our work will also contribute to the overall aims 1, 2, and 4.

类囊体膜支架光合复合物，其将电子转移与质子跨膜运动耦合，从而产生驱动ATP产生的质子动力（PMF，由Δ-pH和Δ-Psi组成）。类囊体结构与高效光合作用密切相关。类囊体是扁平的而不是球形的，增加了每管腔面积的光合复合物的浓度以驱动PMF，同时为可溶性电子载体质体蓝素通过类囊体管腔的扩散提供方向性。然而，类囊体结构不是静态的，并响应光的质量和数量的变化。在蓝细菌、绿色藻类和植物中的初步电子显微镜观察表明，类囊体腔在增加的光强度下膨胀。一个合乎逻辑的假设是，管腔酸化（Δ-pH）和离子通量驱动的膜电位变化（Δ-Psi）可能与扩张管腔的渗透力有关。然而，这种架构变化的确切动态和机制仍然没有被描述。该项目的目标是了解光诱导类囊体肿胀的机制基础和生理后果，并具体测试这种肿胀是如何通过PMF的不同组分进行调制的。这项研究将通过我们先进的冷冻电子断层扫描（cryo-ET）工作流程来实现，我们已经开发了亚纳米精度的天然类囊体结构（膜和管腔宽度），并分析了每个光合复合物沿着这些膜的组织。首先，我们的目标是（i）进行详细的冷冻ET时间序列的野生型细胞从黑暗过渡到不同的光强度后，在绿色藻类（莱茵衣藻）和蓝藻（集胞藻属6803）的类囊体膨胀的动力学特征。接下来，我们的目标（ii）检查的贡献三角洲pH值和三角洲Psi类囊体腔扩张相结合的冷冻ET与小分子离子载体和遗传扰动的ATP合酶和KEA 3离子反向转运蛋白。在平行，我们的目标（iii）测试特定的PMF细胞色素b6 f类囊体腔动力学的贡献。最后，我们的目标（iv）创建一个集成的模型，光依赖的流明扩张相结合，我们的冷冻ET数据与功能测量PMF和光合功能的财团的其他成员。我们项目的重点是实现GoPMF的总体目标3（能量转换系统重塑中类囊体膜的结构动力学）。我们的工作还将有助于实现总体目标1、2和4。