Regulation der Photosynthese für die Stickstoff-Fixierung in Trichodesmium

木藻光合作用固氮的调控

• 批准号: 15846727
• 负责人: Professor Dr. Hendrik Küpper
• 金额: --
• 依托单位: Department of Plant Biochemistry and Biophysics
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/15846727?language=en
• 关键词: Regulation; der; Photosynthese; die; Stickstoff

The filamentous cyanobacterium Trichodesmium carries out photosynthesis and nitrogen fixation during the light period without differentiation of specialised cells. It does so via reversible switching between different activity states including anoxygenic PSII-mediated photosynthesis (via Mehler reaction). This project investigates the physiological mechanisms that regulate photosynthesis for nitrogen fixation. We found that the diel activity pattern is primarily related to reversible biochemical or biophysical modifications of existing pigment-protein complexes, in particular differential (un)coupling of phycobilisomes. Probing this regulation by iron limitation did not lead to downregulation of Fe requiring PS I and nitrogen requiring phycobilisomes, but caused selective downregulation of nitrogenase, and changes in light harvesting complexes like expression of a different isoform of phycoerythrin. Now we want to quantitatively dissect the reversible (un)coupling of phycobilisomes in more detail, isolate and characterisation of the new isoform of phycoerythrin. Additionally, we would like to investigate the physiological importance of the changes in carotenoids that were found in the diel activity cycle and under iron limitation stress. In vivo spatially and spectrally resolved microscopic measurements of UV/VIS fluorescence&absorption kinetics will be supplemented e.g. by protein chromatography, nitrogenase activity measurements and Western blots.

丝状蓝藻Trichodesmium在光照期间进行光合作用和固氮，而不分化出特化细胞。它通过不同活动状态之间的可逆切换来实现这一点，包括无氧 PSII 介导的光合作用（通过梅勒反应）。该项目研究调节光合作用固氮的生理机制。我们发现昼夜活动模式主要与现有色素-蛋白质复合物的可逆生化或生物物理修饰有关，特别是藻胆体的差异（解）偶联。通过铁限制探索这种调节并没有导致需要 PS I 的铁和需要氮的藻胆体的下调，而是引起固氮酶的选择性下调，以及光捕获复合物的变化，例如不同亚型藻红蛋白的表达。现在我们想要更详细地定量剖析藻胆体的可逆（非）偶联，分离和表征新的藻红蛋白亚型。此外，我们还想研究在昼夜活动周期和铁限制胁迫下发现的类胡萝卜素变化的生理重要性。将补充 UV/VIS 荧光和吸收动力学的体内空间和光谱分辨显微测量，例如通过蛋白质色谱、固氮酶活性测量和蛋白质印迹。