14-PSIL MAGIC: a multi-tiered approach to gaining increased carbon

14-PSIL MAGIC：增加碳的多层方法

• 批准号: BB/M01133X/1
• 负责人: Michael Blatt
• 金额: $ 40.82万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FM01133X%2F1
• 关键词: 14; PSIL; MAGIC; multi; tiered

In the Calvin-Benson cycle of plants, the enzyme RuBisCO fixes CO2 to produce two molecules of 3-phosphoglycerate. RuBisCO evolved ~3.6bn years ago in an atmosphere of high CO2 and low O2, with little need to discriminate between the two gases. In today's atmosphere RuBisCO fixes both CO2 and O2. The latter generates phosphoglycolate, which is retrieved by photorespiration but at an energy cost that represents a significant loss in photosynthetic efficiency. One method to reduce O2 fixation by RuBisCO is to raise the partial pressure of CO2. Carbon concentrating mechanisms (CCMs) have evolved multiple times to this end. For example, C4 photosynthesis uses phosphoenol-pyruvate carboxylase (PEPC), an enzyme that does not possess oxygenase activity, to fix HCO3- temporarily in C4 acids; cellular specialization allows release and concentration of CO2 for refixing by RuBisCO. As much as a 50% increase in yield might be realized in crops were O2 fixation by RuBisCO to be bypassed in a similar manner. Significant resources have already gone into engineering RuBisCO for increased CO2 selectivity and into introducing a single-celled version of C4 photosynthesis in rice, but a step change in photosynthetic efficiency has not yet been achieved. Investigators from Universities in the US (John Golbeck (JG), Penn State; and Cheryl Kerfeld (CK), Michigan State) and the UK (Mike Blatt (MB), Glasgow; Nigel Burroughs (NB), Warwick; and Julian Hibberd (JH), Cambridge) participated in an NSF/BBSRC Ideas Laboratory in 2010, at which they proposed a novel strategy to address this problem, a proposal that has since matured to the level of technological implementation. They are now joined by Nick Smirnoff (NS, Exeter) and Manish Kumar (MK, Penn State), who bring additional and key expertise to the project. The research has two themes: a light driven ion pump, composed of halorhodopsin and an anion/HCO3- exchanger, AE1; and the use of artificial scaffolds for channelling CO2 to RuBisCO. A parallel goal is to re-engineer the light-driven ion pump to transport HCO3- directly and to absorb light energy not used by photosynthesis. These efforts are underpinned with mathematical modelling of CO2 delivery and assimilation to direct experimentation based around the following components.Light-Driven Pump. Halorhodopsin (HR) is an integral membrane protein and consists of 7 transmembrane alpha-helices and a bound retinal. The retinal undergoes light-driven bond rotation between 13-cis and all-trans conformations to drive ion transport. HR transports other halides as well, and ion selectivity appears to be a localized feature of the pHR transport site. pHR is sufficiently promiscuous to make engineering a light-driven HCO3- pump a possibility.Anion/Bicarbonate Exchanger: The erythrocyte Band3 protein (AE1) facilitates Cl-/HCO3- exchange across the membrane. It generates a high flux close to equilibrium and is largely insensitive to pH, making it well suited to engineering a HCO3- accumulating mechanism. Most promising for synthetic engineering, the AE1 transporter is functional in mammalian cell cultures, Xenopus oocytes, and yeast without adverse effects on homeostasis or growth. The modular structure of AE1, offers a realistic strategy for coupling HCO3- pumping coupled to pHR-driven Cl- transport.Artificial Scaffolds: CO2 diffusion needs to be constrained locally for sufficient time to allow it to be fixed by RuBisCO. Substrate channelling is found in several natural systems, including plants. Efficiency gains arise from physical proximity and 'sponge'-like buffering that enables transfer of intermediates and minimizes runoff of substrates.

在植物的Calvin-Benson循环中，酶Rubisco固定CO2以产生两个分子的3-磷酸甘油酸分子。 Rubisco在高二氧化碳和低O2的大气中进化了约36亿年，几乎不需要区分两种气体。在当今的大气中，Rubisco固定了CO2和O2。后者产生磷酸乙醇酸酯，该磷酸酸酯是通过光呼吸检索的，但以能量成本代表光合作用效率显着损失。减少Rubisco固定O2的一种方法是增加二氧化碳的部分压力。碳浓缩机制（CCM）已多次演变为此。例如，C4光合作用使用磷酸烯醇 - 丙酮酸羧化酶（PEPC），一种不具有氧酶活性的酶，以暂时固定HCO3-在C4酸中固定。细胞专业化允许释放和浓度CO2，用于rubisco重新构成。在农作物中，鲁比斯科的O2固定在农作物中可能会增加50％的收益率，以类似的方式绕过。工程鲁比斯科（Rubisco）的大量资源已经提高了二氧化碳选择性，并引入了米饭中的C4光合作用的单细胞版本，但是尚未实现光合效率的一步变化。来自美国大学（John Golbeck（JG），宾夕法尼亚州立大学；密歇根州）和英国的Cheryl Kerfeld（John Golbeck（JG））和英国（Mike Blatt（MB），Glasgow; Nigel Burroughs（NB），Warwick； Warwick; julian Hibberd（JH），cambbry ats in n n n a ns af conce，为了解决这个问题，此后已成熟到技术实施水平。现在，Nick Smirnoff（NS，Exeter）和Manish Kumar（MK，Penn State）加入了他们的行列，他们为该项目带来了更多和重要的专业知识。这项研究有两个主题：一个由卤代蛋白和阴离子/HCO3-交换器AE1组成的轻驱动离子泵；以及将人工脚手架用于将二氧化碳引导到Rubisco。一个平行的目标是重新设计光驱动的离子泵直接运输HCO3-并吸收光合作用未使用的光能。这些努力的基础是二氧化碳递送和同化以基于以下组件的直接实验的数学建模。卤代汀（HR）是一种整体膜蛋白，由7个跨膜α-螺旋和一个结合的视网膜组成。视网膜在13-CIS和全反式构象之间进行轻驱动键旋，以驱动离子运输。人力资源也将其他卤化物运输，离子选择性似乎是PHR运输部位的局部特征。 PHR足够混杂，可以使工程发动机驱动的HCO3-泵可能性。Anion/碳酸氢盐交换器：红细胞带3蛋白（AE1）促进了整个膜上的Cl-/hco3-交换。它产生的高通量接近平衡，并且对pH值不敏感，因此非常适合工程HCO3累积的机制。 AE1转运蛋白最有前途的合成工程，可在哺乳动物细胞培养物，爪蟾卵母细胞和酵母中对稳态或生长产生不利影响。 AE1的模块化结构提供了一种现实的策略，用于耦合HCO3-泵送与PHR驱动的Cl-传输耦合。人工支架：二氧化碳扩散需要在本地限制，以便在足够的时间上限制rubisco将其固定。在包括植物在内的几种天然系统中发现了底物通道。效率的提高是由物理接近性和类似海绵的缓冲，可以使中间体转移并最大程度地减少底物的径流。

项目成果

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植物生理学推出副专题编辑。

• DOI: 10.1104/pp.18.00113
• 发表时间: 2018
• 期刊: Plant physiology
• 影响因子: 7.4
• 作者: Blatt MR

When Is Science 'Ultimately Unreliable'?

• DOI: 10.1104/pp.16.00160
• 发表时间: 2016-03-01
• 期刊: PLANT PHYSIOLOGY
• 影响因子: 7.4
• 作者: Blatt, Michael R.

Focus on Water

• DOI: 10.1104/pp.114.900484
• 发表时间: 2014-04-01
• 期刊: PLANT PHYSIOLOGY
• 影响因子: 7.4
• 作者: Blatt, Michael R.;Chaumont, Francois;Farquhar, Graham
• 通讯作者: Farquhar, Graham

What can mechanistic models tell us about guard cells, photosynthesis, and water use efficiency?

• DOI: 10.1016/j.tplants.2021.08.010
• 发表时间: 2022-01-12
• 期刊: TRENDS IN PLANT SCIENCE
• 影响因子: 20.5
• 作者: Blatt, Michael R.;Jezek, Mareike;Hills, Adrian
• 通讯作者: Hills, Adrian

Plant Physiology 90th Anniversary.

植物生理学 90 周年。

• DOI: 10.1104/pp.16.00849
• 发表时间: 2016
• 期刊: Plant physiology
• 影响因子: 7.4
• 作者: Blatt M