Synthesis of Glycogen in Bacteria and Starch in Plants: Evolution and Mechanism of Allosteric Control

细菌中糖原和植物中淀粉的合成：变构控制的进化和机制

• 批准号: 1616851
• 负责人: Miguel Ballicora
• 金额: $ 64万
• 依托单位: Loyola University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1616851&HistoricalAwards=false
• 关键词: Synthesis; Glycogen; Bacteria; Starch; Plants

ADP-glucose pyrophosphorylase is central to starch synthesis in plants and glycogen synthesis in bacteria and other organisms, serving as carbon storage polymers. It is a common biotechnology target and an informed understanding of its regulation has implications for starch/glycogen synthesis in a host of organisms. Allosteric control of ADP-glucose pyrophosphorylase activity is an important but poorly understood regulatory mechanism. Presently it is unclear how the enzyme is allosterically activated and how that activation signal is transmitted structurally within the enzyme. The goal of this project is to perform computational, structural and biochemical studies to understand and characterize the allosteric signals and the interaction of the allosteric effectors on ADP-glucose pyrophosphorylase activity in bacteria as a model for plants. The PIs predict the presence of a common structural element that works as a switch but also the presence of an alternative allosteric signal binding site. This project will also contribute to education by training undergraduate and graduate students, establish international collaborations, and foster participation of underrepresented minorities in research by supporting programs such as McNair-SROP. This project will also support an international course on protein science that includes elements of the research, providing a unique training opportunity for undergraduate and graduate students. Plant starch and bacterial glycogen biosynthetic pathways provide models for the structure and evolution of allosteric regulatory functions of the enzyme ADP-glucose pyrophosphorylase. Despite the importance of these pathways, the allosteric mechanism that controls the activity of this enzyme is largely unknown. The project comprises computational, structural, and biochemical studies to understand and characterize the transmission of the allosteric signal and the interaction of the allosteric effectors in the ADP-glucose pyrophosphorylase family. It is predicted there is both a common structural element that works as a switch and an alternative allosteric signal guided by a secondary site. Three main research objectives will be pursued: 1) screen several enzyme forms from diverse branches of the phylogenetic tree for the presence of a dual allosteric mechanism; 2) obtain crystal structures of allosteric mutants ("switched off") in several different conditions with different ligands to test the hypothesis that certain residues form a conserved allosteric switch in ADP-glucose pyrophosphorylases; and 3) perform computational studies (molecular dynamics, correlated movement analysis, and network pathway analysis) to predict the signaling pathways of activation from each putative allosteric site.

ADP-葡萄糖焦磷酸化酶是植物中淀粉合成和细菌和其他生物中糖原合成的核心，作为碳储存聚合物。它是一个常见的生物技术靶标，对其调节的明智了解对淀粉/糖原的合成有影响。 ADP-葡萄糖焦磷酸化酶活性的变构控制是一种重要但知之甚少的调节机制。 目前，尚不清楚酶如何被变构激活以及该激活信号在酶内的结构上如何传播。该项目的目的是进行计算，结构和生化研究，以理解和表征变构信号以及变构效应子对细菌中ADP-葡萄糖焦磷酸化酶活性的相互作用作为植物模型。 PI预测存在作为开关的共同结构元件的存在，也可以存在替代性变构信号结合位点的存在。该项目还将通过培训本科生和研究生，建立国际合作，并通过支持McNair-Srop之类的计划来促进教育，并建立国际合作，并促进代表性不足的少数群体参与研究。 该项目还将支持包括研究元素在内的蛋白质科学课程，为本科生和研究生提供了独特的培训机会。 植物淀粉和细菌糖原生物合成途径为酶ADP ADP-glucose焦磷酸酶的变构调节功能的结构和演变提供了模型。尽管这些途径很重要，但控制该酶活性的变构机制在很大程度上是未知的。该项目包括计算，结构和生化研究，以理解和表征变构信号的传播以及变构效应子在ADP葡萄糖焦磷酸酶家族中的相互作用。 可以预测，既有一个通用的结构元素，可以用作开关和由次级位点引导的替代变构信号。将实现三个主要的研究目标：1）从系统发育树的不同分支中筛选几种酶形式，以存在双重变构机制； 2）在几种不同的条件下具有不同配体的变构突变体（“关闭”）的晶体结构，以测试某些残基在ADP-葡萄糖焦磷酸酶中形成保守的变构开关的假设； 3）进行计算研究（分子动力学，相关运动分析和网络途径分析），以预测每个假定的变构位点激活的信号传导途径。