Resolving the key photoprotective switch in photosynthetic electron transport

解决光合电子传输中关键的光保护开关

• 批准号: BB/R004838/1
• 负责人: Guy Hanke
• 金额: $ 49.65万
• 依托单位: Queen Mary University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FR004838%2F1
• 关键词: Resolving; key; photoprotective; switch; photosynthetic

We aim to understand the way in which plants are able to adapt to fluctuations in the environment by studying a specific example that has the potential to improve crop plant tolerance to stress. In the final step of photosynthetic electron transfer, the enzyme ferredoxin:NADP(H) oxidoreductase (FNR) uses photosynthetic electrons to reduce NADP+ to NADPH, which is then used in multiple reactions and is essential for C fixation. The amount of this enzyme has a strong effect (a high coefficient of control) on the entire pathway of photosynthesis (0.7 at low light and 0.94 at saturating light (1)). Interestingly, it has also been shown that the amount of FNR also strongly correlates with the ability to tolerate multiple environmental stresses in tobacco (2,3), although the reasons for this are not yet clear. One contributing factor could relate to the free radicals produced by photosynthetic electron transport (PET). We recently showed that variable FNR content and location results in disrupted free radical production, and that this could be responsible for "priming" the plant, and inducing defence mechanisms (4). Although FNR has been well studied as an enzyme, its location within chloroplasts is highly dynamic, with many interaction partners. The reason for these multiple interactions, the activity of the enzyme at these different locations and the relationship of these complexes with the rest of the PET apparatus is not understood. There are three important recent developments that will enable us to answer these important questions. Firstly, we have produced transgenic Arabidopsis plants with FNR proteins localised to different complexes within the chloroplast (5). This means we can now compare the activity of the enzyme, and its associated metabolic pathways, when it is bound to different places. Introduction of cyanobacterial FNR to higher plants has been patented as a means of improving stress tolerance in crop plants, but the interactions of this prokaryotic enzyme in higher plant chloroplasts are unknown. Our novel plants will allow us to pinpoint the interactions responsible for stress tolerance. Secondly, new equipment has been developed that will allow us to monitor the activity of the enzyme inside a living leaf (6), which is much more accurate than working with semi-purified systems, where important components or regulatory events may be lost. Thirdly, we have promising preliminary results from a microscopy approach, that will help us image where in the chloroplast membranes these events occur. This is important, as many regulatory events in chloroplasts can only be understood in the context of spatial organisation between different parts of the organelle, or are too weak to detect with standard biochemical methods.Using these tools we aim to discover how dynamic redistribution of FNR is able to regulate PET and promote stress tolerance. Plants have limited resources available to them, and must allocate these to ensure the greatest chance of survival and reproduction. Improving the efficiency of switching between protective states and assimilatory states will therefore improve the chances of the plant not only surviving stressful conditions, but conducting rapid photosynthesis afterward and achieving a high harvest index. Better understanding of this regulation may help to design or breed plants able to withstand specific stresses, or rapidly respond to the presence and absence of stresses in order to achieve survival but maintain high yields.(1) Hajirezaei MR, et al. (2002) Plant J 29(3):281-93.(2) Palatnik JF, et al. (2003) Plant J 35(3):332-41.(3) Rodriguez RE, et al. (2007) Plant Physiol 143(2):639-49.(4) Kozuleva M, et al. (2016) Plant Physiol 172: 1480-1493.(5) Twachtmann M, et al. (2012) Plant Cell 24(7):2979-91.(6) Klughammer C, et al. (2016) Photosynth Res 128(2):195-214.

我们的目标是通过研究一个有可能提高作物对胁迫耐受性的具体例子，了解植物能够适应环境波动的方式。在光合电子转移的最后一步，铁氧还蛋白：NADP（H）氧化还原酶（FNR）利用光合电子将NADP+还原为NADPH，然后用于多个反应，并且是C固定所必需的。这种酶的量对整个光合作用途径具有强烈的影响（高控制系数）（低光下为0.7，饱和光下为0.94（1））。有趣的是，还表明FNR的量也与烟草耐受多种环境胁迫的能力密切相关（2，3），尽管其原因尚不清楚。其中一个影响因素可能与光合电子传递（PET）产生的自由基有关。我们最近发现，不同的FNR含量和位置导致自由基产生中断，这可能是“引发”植物和诱导防御机制的原因（4）。虽然FNR作为一种酶已经被很好地研究，但它在叶绿体中的位置是高度动态的，有许多相互作用伙伴。这些多重相互作用的原因、酶在这些不同位置的活性以及这些复合物与PET装置其余部分的关系尚不清楚。最近有三个重要的事态发展将使我们能够回答这些重要问题。首先，我们已经产生了FNR蛋白定位于叶绿体内不同复合物的转基因拟南芥植物（5）。这意味着我们现在可以比较酶的活性及其相关的代谢途径，当它被结合到不同的地方。将蓝藻FNR引入高等植物已作为提高作物植物胁迫耐受性的手段获得专利，但这种原核酶在高等植物叶绿体中的相互作用尚不清楚。我们的新植物将使我们能够精确地确定负责胁迫耐受性的相互作用。其次，已经开发了新的设备，使我们能够监测活叶内酶的活性（6），这比使用半纯化系统更准确，其中重要组分或调节事件可能会丢失。第三，我们从显微镜方法中获得了有希望的初步结果，这将有助于我们了解这些事件发生在叶绿体膜中的位置。这是很重要的，因为叶绿体中的许多调节事件只能在细胞器不同部分之间的空间组织的背景下理解，或者太弱而不能用标准的生化方法检测到。使用这些工具，我们的目标是发现FNR的动态再分配如何能够调节PET和促进胁迫耐受性。植物可利用的资源有限，必须分配这些资源以确保最大的生存和繁殖机会。因此，提高保护状态和同化状态之间的转换效率将不仅提高植物在胁迫条件下存活的机会，而且提高植物在胁迫条件下进行快速光合作用并实现高收获指数的机会。更好地了解这一规定可能有助于设计或培育能够承受特定压力的植物，或迅速应对压力的存在和不存在，以实现生存，但保持高产。(1)Hajirezaei MR等人（2002）Plant J 29（3）：281-93. (2)Palatnik JF等人（2003）Plant J 35（3）：332-41. (3)Rodriguez RE等人（2007）Plant Physiol 143（2）：639-49. (4)Kozuleva M等人（2016）Plant Physiol 172：1480-1493. (5)Twachtmann M等人（2012）Plant Cell 24（7）：2979-91. (6)Klughammer C，et al.（2016）Photosynth Res 128（2）：195-214.

项目成果

Protection of photosystem I during sudden light stress depends on ferredoxin:NADP(H) reductase abundance and interactions.

• DOI: 10.1093/plphys/kiab550
• 发表时间: 2022-02-04
• 期刊: Plant physiology
• 影响因子: 7.4
• 作者: Rodriguez-Heredia M;Saccon F;Wilson S;Finazzi G;Ruban AV;Hanke GT
• 通讯作者: Hanke GT

Regulation of photosynthetic electron flow on dark to light transition by ferredoxin:NADP(H) oxidoreductase interactions.

• DOI: 10.7554/elife.56088
• 发表时间: 2021-03-09
• 期刊: eLife
• 影响因子: 7.7
• 作者: Kramer M;Rodriguez-Heredia M;Saccon F;Mosebach L;Twachtmann M;Krieger-Liszkay A;Duffy C;Knell RJ;Finazzi G;Hanke GT
• 通讯作者: Hanke GT

Functional basis of electron transport within photosynthetic complex I.

• DOI: 10.1038/s41467-021-25527-1
• 发表时间: 2021-09-10
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Richardson KH;Wright JJ;Šimėnas M;Thiemann J;Esteves AM;McGuire G;Myers WK;Morton JJL;Hippler M;Nowaczyk MM;Hanke GT;Roessler MM
• 通讯作者: Roessler MM

Physiological Roles of Flavodiiron Proteins and Photorespiration in the Liverwort Marchantia polymorpha.

• DOI: 10.3389/fpls.2021.668805
• 发表时间: 2021
• 期刊: Frontiers in plant science
• 影响因子: 5.6
• 作者: Shimakawa G;Hanawa H;Wada S;Hanke GT;Matsuda Y;Miyake C
• 通讯作者: Miyake C