Artificial membranes as model systems to investigate the temperature adaptation of diatoms

人造膜作为模型系统研究硅藻的温度适应

• 批准号: 212032704
• 负责人: Professor Dr. Reimund Goss
• 金额: --
• 依托单位: Arbeitsgruppe Pflanzenphysiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/212032704?language=en
• 关键词: Artificial; membranes; model; systems; investigate

In the first two years of the project we could show that the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum modulate their lipid composition in adaption to varying environmental conditions. Cultivation of T. pseudonana under lower temperatures induced an increase of the MGDG amount in the thylakoids accompanied by a decreased concentration of DGDG. Measurements of the membrane fluidity indicated that the accumulation of MGDG led to increased membrane fluidity, i.e. loosening of the thylakoid membrane structure. Cultivation under high light conditions strongly increased the percentage of SQDG in the thylakoid membranes and reduced the MGDG content. Furthermore, the total thylakoid lipid concentration, in relation to chlorophyll (Chl), showed an increase. In general, the lipid per Chl ratio is significantly higher in diatom thylakoids compared to higher plants, which indicates either a decreased protein crowding in the diatom membrane or a shift from Chl binding proteins to proteins which are not associated with pigments. This important observation will be addressed in more detail in the third year of the project. Further measurements of the membrane fluidity concentrated on the role of the photoprotective xanthophyll cycle pigment diatoxanthin (Dtx), which is converted from diadinoxanthin (Ddx) by the enzyme Ddx de-epoxidase under HL conditions. We found that in HL thylakoids of P. tricornutum, with a high amount of free Dtx in the lipid phase of the membrane, Dtx leads to increased membrane rigidity in comparison to thylakoids which mainly contain Ddx. In the third year of the project we plan a detailed analysis of the other factors which influence the fluidity of the diatom thylakoid membrane with a special focus on the fatty acid composition and the negative charge of the anionic lipids which dominate the diatom membrane. In the first two years of the project we have developed methods for the analysis of diatom lipids and fatty acids by means of HPLC coupled with a CAD detector. We have also developed a method for the isolation of native diatom lipids and fatty acids which will now be used for the construction of artificial membrane systems. Besides measurements of the membrane fluidity, these liposomes will be used to study the effect of differences in the lipid and fatty acid composition on Ddx de-epoxidation and the structure of light-harvesting complexes (FCPs). During the first two years of the project we could also show that aggregation of the FCPs depends on low pH-values and the presence of Dtx. High concentrations of Mg2+ ions lead to further aggregation of the complexes. In the third year of the project high Mg2+ concentrations and low pH-values will also be used in measurements of the membrane fluidity and Ddx de-epoxidation to compensate the negative charges of the lipids SQDG and PG. This will allow us to determine if the negative head-groups of the anionic lipids play a role in these processes.

在项目的头两年，我们可以证明硅藻假海藻和三角褐指藻调节它们的脂质组成以适应不同的环境条件。低温培养诱导假单胞菌类囊体中MGDG含量增加，DGDG浓度降低。膜流动性测量表明，MGDG的积累导致膜流动性增加，即类囊体膜结构松动。在强光条件下培养可显著提高类囊体膜中SQDG的百分比，降低MGDG的含量。此外，总类囊体脂质浓度与叶绿素（Chl）的关系也有所增加。总的来说，与高等植物相比，硅藻类囊体的脂质/ Chl比率明显更高，这表明硅藻膜中的蛋白质拥挤减少或从Chl结合蛋白转向与色素无关的蛋白质。这个重要的观察结果将在项目的第三年更详细地讨论。对膜流动性的进一步测量集中在光保护叶黄素循环色素diatoxanthin （Dtx）的作用上，Dtx在HL条件下通过Ddx去环氧化酶从diadinoxanthin （Ddx）转化而来。我们发现，与主要含有Ddx的类囊体相比，在三角草HL类囊体中，膜脂相中含有大量游离Dtx， Dtx导致膜刚性增加。在项目的第三年，我们计划详细分析影响硅藻类囊体膜流动性的其他因素，特别关注脂肪酸组成和主导硅藻膜的阴离子脂质的负电荷。在项目的前两年，我们开发了用HPLC和CAD检测器结合的方法来分析硅藻脂和脂肪酸。我们还开发了一种分离天然硅藻脂和脂肪酸的方法，这些方法现在将用于构建人工膜系统。除了测量膜流动性外，这些脂质体还将用于研究脂质和脂肪酸组成差异对Ddx去环氧化和光收集复合物（fcp）结构的影响。在项目的头两年，我们还可以证明fcp的聚集取决于低ph值和Dtx的存在。高浓度的Mg2+离子导致复合物进一步聚集。在项目的第三年，高Mg2+浓度和低ph值也将用于测量膜流动性和Ddx去环氧化，以补偿脂质SQDG和PG的负电荷。这将使我们能够确定阴离子脂质的负头基是否在这些过程中发挥作用。

项目成果

The diadinoxanthin diatoxanthin cycle induces structural rearrangements of the isolated FCP antenna complexes of the pennate diatom Phaeodactylum tricornutum.

二氮黄素二氮黄素循环诱导羽状硅藻三角褐指藻分离的 FCP 天线复合物的结构重排

• DOI: 10.1016/j.plaphy.2015.09.002
• 发表时间: 2015
• 期刊: Plant physiology and biochemistry : PPB
• 作者: Schaller-Laudel S;Volke D;Redlich M;Kansy M;Hoffmann R;Wilhelm C;Goss R
• 通讯作者: Goss R

Influence of thylakoid membrane lipids on the structure of aggregated light-harvesting complexes of the diatom Thalassiosira pseudonana and the green alga Mantoniella squamata.

• DOI: 10.1111/ppl.12565
• 发表时间: 2017-07
• 期刊: Physiologia plantarum
• 影响因子: 6.4
• 作者: Susann Schaller-Laudel;D. Latowski;M. Jemioła-Rzemińska;K. Strzałka;Sebastian Daum;K. Bacia;C. Wilhelm;R. Goss

Influence of pH, Mg2+, and lipid composition on the aggregation state of the diatom FCP in comparison to the LHCII of vascular plants

• DOI: 10.1007/s11120-013-9951-x
• 发表时间: 2014-03-01
• 期刊: PHOTOSYNTHESIS RESEARCH
• 影响因子: 3.7
• 作者: Schaller, Susann;Richter, Konstantin;Goss, Reimund
• 通讯作者: Goss, Reimund