The Core Metabolism of Rhodobacter sphaeroides

球形红杆菌的核心代谢

• 批准号: 1516933
• 负责人: Birgit Alber
• 金额: $ 33.26万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1516933&HistoricalAwards=false
• 关键词: Core; Metabolism; Rhodobacter; sphaeroides

Carbon is an essential element for all known forms of life. Nearly all important cellular constituents contain carbon compounds and in many organisms these carbon-containing biomolecules are simultaneously used to obtain energy for growth. Carbon-containing biomolecules are converted into smaller molecules (precursor metabolites) that are key components for the major chemical reactions (metabolism) of living organisms. These precursor metabolites can then serve either as the building blocks for other cellular constituents or can be broken down in chemical reactions that generate energy. These different uses of carbon-containing biomolecules occur regardless of the carbon sources that are used by microbes for their growth and energy requirements. Consequently, it is essential to understand the processes by which the chemical reactions of precursor metabolites are controlled so that carbon can flow towards the molecules that will be used to build cells. This knowledge will enable the more efficient use of microorganisms to generate useful products, including those (such as biofuels) of biotechnological importance. This project will generate fundamental new information on how carbon is used in living systems, and through classroom and research experiences will provide interdisciplinary training to the next generation of scientists, including undergraduate and graduate students, in microbial physiology and genetics. For every carbon substrate, the levels of the precursor metabolites pyruvate (C3), phosphoenolpyruvate (C3), and oxaloacetate (C4) have to be controlled: this is referred to as the C4/C3 node. Importantly, the pathways leading to these metabolites, as well as their fate, differ depending on where a given substrate has entered central carbon metabolism. In this project the regulation and activity of enzymes involved in the partition of carbon at the C4/C3 node will be examined and the question of why several enzymes apparently catalyzing the same reaction are active at the same time will be addressed. Rhodobacter sphaeroides will be used to expand our knowledge of assimilation of carbon since it is possible to disconnect energy metabolism from carbon assimilation during anoxygenic photoheterotrophic growth of this organism. R. sphaeroides is ideally suited for this study given its versatility in utilizing a wide spectrum of carbon substrates. This research will be used to determine the reactions required for 1) the conversion of C4- to C3-precursor metabolites under different growth conditions and 2) the inter-conversion of pyruvate and phosphoenolpyruvate. By capitalizing on the genetic tractability of R. sphaeroides mutants will be constructed for comparative experiments analyzing which specific enzymes are required under particular growth conditions. In addition, biochemical analyses of recombinant proteins will determine kinetic parameters, potential heteromeric composition, cofactor specificity, and posttranslational regulation of enzymes at the C4/C3 node.

碳是所有已知生命形式的基本元素。几乎所有重要的细胞成分都含有碳化合物，在许多生物体中，这些含碳生物分子同时用于获得生长所需的能量。含碳生物分子转化为更小的分子（前体代谢物），这些分子是生物体主要化学反应（代谢）的关键成分。然后，这些前体代谢物可以作为其他细胞成分的构建块，或者可以在产生能量的化学反应中被分解。含碳生物分子的这些不同用途与微生物用于其生长和能量需求的碳源无关。因此，必须了解控制前体代谢物的化学反应的过程，以便碳可以流向用于构建细胞的分子。这一知识将使微生物能够更有效地利用，以产生有用的产品，包括具有生物技术重要性的产品（如生物燃料）。该项目将产生关于碳如何在生命系统中使用的基本新信息，并通过课堂和研究经验，为下一代科学家，包括本科生和研究生，提供微生物生理学和遗传学方面的跨学科培训。对于每种碳底物，前体代谢物丙酮酸（C3）、磷酸烯醇丙酮酸（C3）和草酰乙酸（C4）的水平必须得到控制：这被称为C4/C3节点。重要的是，导致这些代谢物的途径以及它们的命运取决于给定底物进入中心碳代谢的位置。在本项目中，将检查参与C4/C3节点碳分配的酶的调节和活性，并解决为什么几种明显催化相同反应的酶同时具有活性的问题。球形红细菌将用于扩大我们的知识同化的碳，因为它是可能的断开能量代谢从碳同化过程中缺氧光合异养生长的这种生物体。R. sphaeroides理想地适合于这种研究，因为它在利用广谱碳底物方面具有多功能性。本研究将用于确定1）在不同生长条件下C4-至C3-前体代谢物的转化和2）丙酮酸和磷酸烯醇丙酮酸的相互转化所需的反应。利用R.将构建类球酵母突变体用于比较实验，分析在特定生长条件下需要哪些特定酶。此外，重组蛋白的生化分析将确定动力学参数，潜在的异聚体组成，辅因子特异性，和酶在C4/C3节点的翻译后调节。