温泉红藻藻胆体-光系统I结合应对缺铁胁迫的能量补偿机制研究

光能的捕获与消散是藻类和植物适应环境变化的关键，通过捕光天线与光系统的动态结合可实现对太阳能的高效捕获与及时消散。温泉红藻具备藻胆体(PBS)和LHCR两类捕光天线，能够在极端酸性、高温环境生存，与PBS和LHCR灵活的作用机制有关，然而它们在胁迫环境中的功能仍不清楚。我们前期研究发现温泉红藻光系统(PS)I周围可结合3或5个LHCR，缺铁胁迫时PBS与PSI之间能量传递增强并形成PBS-PSI超分子复合物。为了揭示PBS-PSI-LHCR(PPL)的工作机理，我们将利用叶绿素荧光和生化技术研究缺铁胁迫对温泉红藻的光合功能破坏；通过BN-PAGE和Western杂交分析PPL的形成过程；分离PPL超分子复合体并鉴定其组分，研究PPL内部以及PBS与PSI-LHCR之间的蛋白质互作网络，解析PPL应对缺铁胁迫的能量捕获与消散机制。此研究将为藻类和植物应对胁迫条件的光合响应机制提供有益启示。

The light harvesting and dissipation is the key for algae and plants to adapt to environmental changes. The dynamic combination of light-harvesting antenna system and photosystems can realize the efficient capture and timely dissipation of solar energy, which is of great significance for algae and plants to adapt to stress environment. Red algae which thrive in acidic hot springs contain two types of light-harvesting antenna systems, the phycobilisome (PBS) and chlorophyll a binding polypeptides (termed LHCR). Red algae can survive in extremely acidic (pH 0.2-4) and high-temperature (40-56℃) environment, which is related to the flexible light harvesting and dissipation function of PBS and LHCR. However, the harvesting and dissipation function of PBS and LHCR in stress environments is still unclear. We have found that each PSI core can bind 3 or 5 LHCRs in the extremophilic unicellular red alga Cyanidioschyzon merolae. Energy transfer between PBS and PSI was enhanced when suffering from long-term iron deficiency. PBS could combine with PSI to form PBS-PSI supramolecular complex, which may play an important role in coping with iron deficiency stress. In order to reveal the working mechanism of PBS-PSI-LHCR, we will use chlorophyll fluorescence and biochemical analysis to study the effect of iron deficiency stress on the photosynthetic function of Cyanidioschyzon merolae. The formation process of PBS-PSI-LHCR supramolecular complex will be analyzed by BN-PAGE and Western blot. Further more, we will isolate the PBS-PSI-LHCR supramolecular complex and identify the protein subunits. Finally, the protein interaction network and machnism of light harvesting and dissipation within the supramolecular complex and between PBS and PSI-LHCR will be studied to clarify the photosynthetic compensation mechanism of PBS-PSI-LHCR in response to iron deficiency stress. This study will provide new insights into the photosynthesis mechanism of algae and plants in response to stress conditions.