Artificial membranes as model systems for the investigation of lipid protein interactions in the thylakoid membranes of vascular plants and the green alga Mantoniella squamata

申请中概述的实验被认为是对DFG项目前两年结果的补充。为了进一步研究类囊体脂质MGDG对LHCII相关的紫黄质（Vx）的脱环氧化的重要性，我们希望将不同的LHCII掺入由双层（DGDG，PC）和反向六方相形成脂质（MGDG，PE）构建的脂质体中。这些脂质体将在脱环氧化测定中用不同的分离的紫黄质脱环氧化酶进行测试。这些实验对于理解VX体内脱环氧化具有重要意义，因为所定义的脂质体类似于天然类囊体膜中的情况。脂质体也将由中性（MGDG，DGDG）和带负电荷的脂质（SQDG，PG）构建，以进一步研究脂质对LHCII结构的影响。这些实验应该支持我们的观察，带负电荷的脂质导致一个强大的解聚的LHCII，而中性脂质稳定的高阶结构，从而意味着在天然膜特殊的脂质结构域存在。我们还将重点介绍原始的绿色装饰。我们希望在有鳞类中进行与上述维管植物LHCII相似的实验。该项目的第三年还将包括M.鳞，特别侧重于类囊体脂质的脂肪酸组成和新发现的DGTA。最后，从M.将制备鳞片以分析具有不同饱和度的脂肪酸对Vx脱环氧化的影响。

The experiments outlined in the application are thought to complement the results of the first two years of the DFG project. To further study the importance of the thylakoid lipid MGDG for the de-epoxidation of LHCII-associated violaxanthin (Vx), we want to incorporate different LHCIIs into liposomes constructed of bilayer (DGDG, PC) and inverted hexagonal phase forming lipids (MGDG, PE). These liposomes will be tested in de-epoxidation assays with different isolated violaxanthin de-epoxidases. The experiments are of importance for the understanding of Vx de-epoxidation in-vivo, as the defined liposomes resemble the situation in the natural thylakoid membrane. Liposomes will also be constructed from neutral (MGDG, DGDG) and negatively charged lipids (SQDG, PG) to further study the lipid effect on the structure of the LHCII. These experiments should support our observation that negatively charged lipids lead to a strong disaggregation of the LHCII, whereas neutral lipids stabilize the higher order structure, thus implying that in the native membrane special lipid domains exist. We will also focus on the primitive green alga M. squamata, where we want to perform comparable experiments as outlined above for the vascular plant LHCII. The third year of the project will also include a quantitative lipid analysis of M. squamata, with a special focus on the fatty acid composition of thylakoid lipids and the newly found DGTA. Finally, native MGDG from M. squamata will be prepared to analyse the effect of fatty acids with a different degree of saturation on the Vx de-epoxidation.