Re-cycling of glycolate in C3-chloroplasts: Biochemical and physiological effects on plant metabolism

C3-叶绿体中乙醇酸的再循环：对植物代谢的生化和生理影响

• 批准号: 5387331
• 负责人: Professorin Dr. Veronica Maurino
• 金额: --
• 依托单位: Abteilung Molekulare Pflanzenphysiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2005-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5387331?language=en
• 关键词: Re; cycling; glycolate; C3; chloroplasts

The C2-cycle of photosynthetic carbon metabolism starts with the oxygenase reaction catalysed by ribulose 1.5-bisphosphate carxboxylase/oxygenase (Bubiosco). The prime function of the C2-pathway is to salvage glycolate 2-P by conversion to glycerate 3-P, which re-enters the C3-reductive cycle. Both CO2 and NH3 are released within the mitochondria, resulting in a loss of at least 25% of the CO2 fixed in abient air in C3-plants. We attempt to introduce two alternative and complete glycolate catabolic cycles into chloroplasts of the model plant A. thaliana (wild-type and a photorespiratory mutant) in order to release and re-fix the CO2 directly within the chloroplast thereby reducing the oxygenase activity of Rubisco by increasing the CO2/O2 ratio. Thus, an autoregulatory cycle would be created which results in an attenuation of the photorespiratory pathway and an expected improvement in the efficiency of CO2 assimilation. Analyses of transformants bearing single transgenes and those with fully operational glycolate cycles will generate data to complement our understanding of function and regulation of the photorespiratory pathway and its interaction with other processes such as the C3-cycle, the anaplerotic flow into organic acids an NH3 refixation.

光合作用碳代谢的C2循环始于核酮糖1.5-二磷酸羧化酶/加氧酶(Bubiosco)催化的加氧酶反应。C2途径的主要功能是通过转化为甘油3-P来挽救乙醇酸2-P，从而重新进入C3还原循环。在C3植物中，二氧化碳和NH3都在线粒体内释放，导致固定在恶劣空气中的二氧化碳损失至少25%。我们试图在模式植物拟南芥(A.thaliana)(野生型和光呼吸突变体)的叶绿体中引入两个交替的完整的乙醇酸分解代谢循环，以便直接释放和重新固定CO2在叶绿体中，从而通过增加CO2/O2比来降低Rubisco的加氧酶活性。因此，将建立一个自动调节循环，导致光呼吸途径的衰减，并预期二氧化碳同化效率的提高。对含有单一转基因和具有完全运作的乙醇酸循环的转化子的分析将产生数据，以补充我们对光呼吸途径的功能和调节及其与其他过程的相互作用的理解，如C3循环、向有机酸的逆流和NH3重固定。