Components of the CO2-Concentrating System

CO2 浓缩系统的组件

• 批准号: 8816796
• 负责人: Martin Spalding
• 金额: $ 19.37万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-03-01 至 1992-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8816796&HistoricalAwards=false
• 关键词: Components; CO2; Concentrating; System

By comparison with C3 plants, Chlamydomonas reinhardtii and other unicellular algae exhibit unusual photosynthetic characteristics. It has been proposed that these characteristics result from the operation of a CO2- concentrating system, which increases the intracellular CO2 concentration to a level which suppresses photorespiration by competitive inhibition of RuBP oxygenase. One of the principal components of the proposed system is a protein which catalyzes the active transport of inorganic carbon across either the plasmalemma or the chloroplast envelope. However, direct, physical evidence for the existence of this transporter, or any other component of the CO2-concentrating system other than carbonic anhydrase, is lacking. Activity of the CO2-concentrating system is under environmental control. Cells grown at limiting CO2 concentrations (air- adapted) show activity, but cells grown at elevated CO2 concentrations (CO2-enriched) show no activity of the CO2- concentrating system. We have identified 7 polypeptides which increase in abundance during adaptation to limiting CO2 concentrations or are specific for cells grown under such conditions. We will continue to extend these observations to comparisons between wild-type and mutants of Chlamydomonas deficient in the CO2-concentrating system to help identify which polypeptides might be involved directly in inorganic carbon accumulation. Using antibodies generated against one or more of these "air-specific" polypeptides, we expect to: (1) determine whether appearance of the "air-specific" polypeptides during "induction" of the CO2-concentrating system correlates with the appearance of the capacity for inorganic carbon accumulation, (2) determine the intracellular location of the corresponding antigens, (3) determine whether Chlamydomonas mutants deficient in the capacity for inorganic carbon accumulation contain polypeptides immunologically cross-reactive with these antibodies, (4) investigate the appearance of translatable mRNA for "air-specific" polypeptides during the "induction" of the CO2-concentrating system. Genes differentially expressed during adaptation of CO2-enriched cells to limiting CO2 will be identified by differential screening of a cDNA library and, if time permits, by molecular cloning of the genes corresponding to the "air-induced" polypeptides. Attainment of all objectives will allow us to better assess the potential for transferring the CO2-concentrating system into higher plants. Some algae can take up carbon dioxide dissolved in water and photosynthesize sugars. How they concentrate the dissolved gas is unknown but could be an important trait to introduce into higher plants. This work investigates the mechanism of uptake and its subsequent enhancement of photosynthesis.***//

与C_3植物相比，莱茵衣藻和 其他单细胞藻类表现出不寻常的光合作用 特色 有人提出，这些 特性的结果，从操作的CO2- 浓缩系统，增加细胞内CO2 浓度达到抑制光呼吸的水平， RuBP加氧酶的竞争性抑制。 之一 所提出的系统的主要成分是蛋白质 它催化无机碳的主动运输 穿过质膜或叶绿体被膜。 然而，直接的，物理证据的存在， 转运体或CO2浓缩装置的任何其他组分 除碳酸酐酶外，缺乏其他系统。 活动 CO2浓缩系统在环境条件下 控制 在限制CO2浓度下生长的细胞（空气- 适应）显示活性，但细胞生长在升高的CO2 浓度（CO2-富集）显示CO2- 浓缩系统 我们已经鉴定了7种多肽 在适应限制二氧化碳排放的过程中， 浓度或对于在这种浓度下生长的细胞是特异性的。 条件 我们将继续把这些观察扩展到 衣原体野生型和突变体的比较 二氧化碳浓缩系统的不足，以帮助确定 哪些多肽可能直接参与无机 碳积累 利用产生的抗体 或更多的这些“空气特异性”多肽，我们期望： (1)确定是否出现“空气特定” 在CO2浓缩的“诱导”过程中， 系统与能力的外观相关， 无机碳积累，（2）确定 相应抗原的细胞内定位，（3） 确定衣原体突变体是否缺乏 无机碳积累容量 与这些多肽免疫交叉反应的多肽 抗体，（4）调查可翻译的外观 “诱导”期间“空气特异性”多肽的mRNA CO2浓缩系统 基因差异 在CO2富集的细胞适应限制的过程中表达 将通过cDNA的差异筛选来鉴定CO2 文库，如果时间允许，通过分子克隆， 对应于“空气诱导的”多肽的基因。 实现所有目标将使我们能够更好地评估 将二氧化碳浓缩系统 转化为高等植物。 一些藻类可以吸收溶解在水中的二氧化碳， 光合作用合成糖。 他们如何将溶解的 气体是未知的，但可能是一个重要的特征， 转化为高等植物。 本工作探讨了 吸收及其随后的光合作用的增强。*//