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.

在植物的卡尔文-本森循环中，RuBisCO 酶固定 CO2，产生两个 3-磷酸甘油酸分子。 RuBisCO 大约 36 亿年前在高二氧化碳和低氧气的大气中形成，几乎不需要区分这两种气体。在当今的大气中，RuBisCO 可以固定 CO2 和 O2。后者产生磷酸乙醇酸，可通过光呼吸回收，但能量消耗意味着光合作用效率的显着损失。减少 RuBisCO 固定 O2 的一种方法是提高 CO2 的分压。为此，碳浓缩机制（CCM）已经多次发展。例如，C4光合作用使用磷酸烯醇丙酮酸羧化酶（PEPC）（一种不具有加氧酶活性的酶）将HCO3-暂时固定在C4酸中；细胞特化允许释放和浓缩 CO2，以便由 RuBisCO 重新固定。如果以类似的方式绕过 RuBisCO 的 O2 固定作用，农作物的产量可能会增加 50%。大量资源已经投入到RuBisCO工程中，以提高二氧化碳选择性，并在水稻中引入单细胞版本的C4光合作用，但光合作用效率尚未实现阶跃改变。来自美国大学（宾夕法尼亚州立大学的 John Golbeck (JG)；密歇根州立大学的 Cheryl Kerfeld (CK)）和英国大学（格拉斯哥的 Mike Blatt (MB)；沃里克大学的 Nigel Burroughs (NB)；和朱利安希伯德 (Julian Hibberd) 的研究人员JH）（剑桥大学）于 2010 年参加了 NSF/BBSRC 创意实验室，他们在会上提出了解决这一问题的新策略，该提案已得到广泛认可现已成熟到技术实施水平。现在尼克·斯米尔诺夫（Nick Smirnoff，国民服役，埃克塞特）和马尼什·库马尔（Manish Kumar，MK，宾夕法尼亚州立大学）也加入了他们的行列，他们为该项目带来了额外的关键专业知识。该研究有两个主题：光驱动离子泵，由盐视紫红质和阴离子/HCO3-交换器AE1组成；以及使用人工支架将二氧化碳引导至RuBisCO。一个并行的目标是重新设计光驱动离子泵，以直接运输 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输送的数学模型以及基于以下组件的直接实验的同化。光驱动泵。盐视紫红质 (HR) 是一种完整的膜蛋白，由 7 个跨膜 α 螺旋和结合的视网膜组成。视网膜在 13-顺式和全反式构象之间经历光驱动的键旋转，以驱动离子传输。 HR 还传输其他卤化物，离子选择性似乎是 pHR 传输位点的局部特征。 pHR 的混杂性足以使设计光驱动的 HCO3- 泵成为可能。 阴离子/碳酸氢盐交换器：红细胞 Band3 蛋白 (AE1) 促进 Cl-/HCO3- 跨膜交换。它产生接近平衡的高通量，并且对 pH 值基本上不敏感，因此非常适合设计 HCO3 积累机制。最有希望用于合成工程的是，AE1 转运蛋白在哺乳动物细胞培养物、非洲爪蟾卵母细胞和酵母中发挥作用，且不会对体内平衡或生长产生不利影响。 AE1 的模块化结构提供了一种将 HCO3- 泵送与 pHR 驱动的 Cl- 运输耦合的现实策略。人工支架：CO2 扩散需要在局部受到足够的时间限制，以使其能够被 RuBisCO 固定。底物通道存在于包括植物在内的多种自然系统中。物理接近性和“海绵”般的缓冲可实现中间体的转移并最大限度地减少基材的流失，从而提高效率。

项目成果

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• 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

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• 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.

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

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• DOI: 10.1104/pp.114.900484
• 发表时间: 2014-04-01
• 期刊: PLANT PHYSIOLOGY
• 影响因子: 7.4
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幕后新面孔。

• DOI: 10.1104/pp.18.00140
• 发表时间: 2018
• 期刊: Plant physiology
• 影响因子: 7.4
• 作者: Blatt MR