21ENGBIO: Re-engineering amino acid metabolism in wheat grain

21ENGBIO：重新设计小麦籽粒中的氨基酸代谢

基本信息

批准号：
BB/W011999/1
负责人：
Nigel Halford
金额：
$ 12.74万
依托单位：
Rothamsted Research
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2022
资助国家：
英国
起止时间：
2022 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FW011999%2F1
关键词：
21ENGBIO Re engineering amino acid

项目摘要

Lysine is one of the 20 amino acids used to make proteins and most animals, including humans, cannot make it, so rely on acquiring it through their diet. Unfortunately, cereal grains contain low concentrations of lysine, resulting in nutrient deficiency in humans and farm animals, such as pigs and chickens, that are dependent on cereal grain for their nutrition. This has resulted in imported soybeans taking much of the market for pig and chicken feed manufacture in the UK and EU, while in developing countries, lysine deficiency is a major cause of malnutrition in people who are reliant on cereal grains for their protein intake. Lysine deficiency does not occur in people in developed countries because they can acquire lysine from meat, but the National Food Strategy (2021) considers current levels of meat consumption to be unsustainable. Reducing our dependence on meat for lysine intake will require the development of a sustainable and readily-available global supply of plant-sourced lysine, which will be unachievable without major changes to the structure of global agricultural production and agri-food systems, unless cereals can be re-engineered to accumulate higher concentrations of lysine in their grains. This project will use genome editing with CRISPR to produce high lysine, non-GM wheat lines. Lysine is synthesised from another amino acid, aspartate, via a multistep biochemical pathway. The key control point is a reaction catalysed by an enzyme called DHDPS. DHDPS is feedback-inhibited by lysine, which binds to the enzyme, and we will edit a wheat DHDPS gene so that the enzyme it encodes no longer binds lysine. We will do this in wheat that has already been edited and has high concentrations of aspartate in the grain, using selection agents that will enable us to identify plants containing a lysine-insensitive DHDPS. These agents include a lysine analogue that competes with lysine for incorporation into proteins, and compounds that inhibit DHDPS itself. These compounds will have to be synthesised and our team will include a synthetic chemist as well as plant molecular biologists and Rothamsted's Cereal Transformation Team, making it genuinely multidisciplinary. Crucially, the inhibitors bind DHDPS over the lysine binding site and we have designed changes that will not only render DHDPS lysine-insensitive but also make it resistant to the inhibitors. The stacking of multiple edits to re-engineer amino acid biosynthesis in wheat grain makes the project an excellent fit for the bioengineered cells and systems theme of the call. The editing will require a technique called homology-directed repair, a technology that has been applied successfully in barley and maize but has not yet been used successfully in wheat, so very much a breakthrough technology. Overall, the project is high risk but high gain, with huge potential international impact, in developed as well as developing countries, affecting human nutritional status, animal feed manufacture, bioethanol production through improved animal feed co-product, market expansion for UK wheat grain, and an increase in availability of plant-derived lysine.

赖氨酸是用于制造蛋白质的 20 种氨基酸之一，大多数动物（包括人类）无法制造赖氨酸，因此只能通过饮食获取赖氨酸。不幸的是，谷物中的赖氨酸浓度较低，导致人类和农场动物（例如猪和鸡）营养缺乏，这些动物的营养依赖于谷物。这导致进口大豆占据了英国和欧盟猪和鸡饲料生产的大部分市场，而在发展中国家，赖氨酸缺乏是依赖谷物获取蛋白质的人们营养不良的主要原因。发达国家的人们不会出现赖氨酸缺乏症，因为他们可以从肉类中获取赖氨酸，但国家粮食战略（2021）认为目前的肉类消费水平是不可持续的。减少我们对肉类赖氨酸摄入的依赖需要开发可持续且易于获得的全球植物源赖氨酸供应，如果全球农业生产和农业食品系统的结构不发生重大变化，这一目标将无法实现，除非谷物能够被重新设计以在谷物中积累更高浓度的赖氨酸。该项目将使用 CRISPR 进行基因组编辑来生产高赖氨酸的非转基因小麦品系。赖氨酸是由另一种氨基酸天冬氨酸通过多步生化途径合成的。关键控制点是由 DHDPS 酶催化的反应。 DHDPS 受到赖氨酸的反馈抑制，赖氨酸与该酶结合，我们将编辑小麦 DHDPS 基因，使其编码的酶不再与赖氨酸结合。我们将在已经经过编辑且谷物中天冬氨酸浓度很高的小麦中进行此操作，使用选择剂，使我们能够识别含有赖氨酸不敏感 DHDPS 的植物。这些药物包括与赖氨酸竞争掺入蛋白质的赖氨酸类似物，以及抑制 DHDPS 本身的化合物。这些化合物必须被合成，我们的团队将包括合成化学家、植物分子生物学家和洛桑的谷物转化团队，使其成为真正的多学科团队。至关重要的是，抑制剂在赖氨酸结合位点上结合 DHDPS，我们设计的改变不仅使 DHDPS 对赖氨酸不敏感，而且使其对抑制剂具有抗性。通过多次编辑来重新设计小麦籽粒中的氨基酸生物合成，该项目非常适合此次电话会议的生物工程细胞和系统主题。编辑需要一种称为同源定向修复的技术，该技术已成功应用于大麦和玉米，但尚未成功应用于小麦，因此是一项突破性技术。总体而言，该项目风险高但收益高，在发达国家和发展中国家都具有巨大的潜在国际影响力，影响人类营养状况、动物饲料生产、通过改进动物饲料副产品生产生物乙醇、英国小麦谷物市场扩张，以及植物来源的赖氨酸的可用性增加。