Light responses of animal-like cryptochromes and aureochromes from microalgae

微藻类动物隐花色素和金色素的光反应

• 批准号: 146946622
• 负责人: Professor Dr. Tilman Kottke
• 金额: --
• 依托单位: Arbeitsgruppe Biophysikalische Chemie und Diagnostik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/146946622?language=en
• 关键词: Light; responses; animal; like; cryptochromes

Cryptochromes and aureochromes are plant photosensors incorporating a flavin as a chromophore. The mechanism and the role of these receptors in microalgae remain largely unclear. Cryptochromes regulate blue-light-dependent processes such as photomorphogenesis and circadian rhythm in higher plants. In the green alga Chlamydomonas reinhardtii, however, an additional animal-like cryptochrome (aCRY) is found. aCRY is currently the only sensory flavoprotein, which is activated not only by blue but also by red light. The structural basis of this unique red-light sensitivity of aCRY needs to be elucidated. We have demonstrated that heterologously expressed aCRY forms a neutral radical of flavin with an absorption spectrum similar to the spectral response in vivo. The neutral radical state was therefore postulated as dark state. The influence of reductants and point mutations on formation and stabilisation of this dark state will be investigated. The course of the photoreaction will be followed by time-resolved spectroscopy. aCRY differs from homologous proteins with a function as core clock component or DNA repair enzyme in a specific C-terminal extension. Infrared difference spectroscopy will be applied to search for lightdependent structural changes in this extension. Further promising candidates for sensory cryptochromes from microalgae will be characterized by spectroscopy. Aureochromes have only been identified in algae up to now including the diatom Phaeodactylum tricornutum. Aureochrome differs from all other proteins containing LOV (light-, oxygen-, or voltage-sensitive) domains such as phototropin in a reverse arrangement of effector and sensor domains. We have shown that despite the reverse arrangement, the C-terminal LOV-J(alpha) helix unfolds in aureochrome similar to phototropin. We will investigate the progress of signal transfer by the J(alpha) helix or other segments in the full-length AUREO1a using infrared double difference spectroscopy. The DNA binding ability of the putative transcription factor will be studied. Other aureochromes from P. tricornutum will be heterologously expressed and their photochemical properties will be analyzed with respect to their role in vivo. The investigation of the novel pathways of signal transfer in these aureochromes and cryptochromes will significantly broaden our current understanding of photosensors.

隐花色素和金色色素是植物光传感器，含有黄素作为发色团。这些受体在微藻中的机制和作用在很大程度上仍不清楚。隐花色素调节蓝光依赖的过程，如高等植物的光形态建成和昼夜节律。然而，在绿色的莱茵衣藻中，发现了一种额外的动物样隐色素（aCRY）。aCRY是目前唯一的感觉黄素蛋白，它不仅被蓝光激活，而且被红光激活。aCRY这种独特的红光敏感性的结构基础需要阐明。我们已经证明，异源表达的aCRY形成一个中性自由基的黄素与吸收光谱类似的光谱响应在体内。因此，中性自由基状态被假定为暗态。还原剂和点突变的形成和稳定的这种黑暗的状态的影响将进行调查。光反应的过程将通过时间分辨光谱学来跟踪。aCRY在特定的C-末端延伸中不同于具有核心时钟组分或DNA修复酶功能的同源蛋白。红外差光谱将被应用于寻找光依赖的结构变化在此扩展。进一步有前途的候选人的感觉隐花色素从微藻将其特征在于光谱。到目前为止，仅在藻类中发现了金色素，包括硅藻三角褐指藻。金色素不同于所有其他含有LOV（光、氧或电压敏感）结构域的蛋白质，如效应器和传感器结构域的反向排列的光致蛋白。我们已经表明，尽管相反的安排，C-末端LOV-J（α）螺旋展开类似于phototropin的aureochrome。我们将使用红外双差光谱研究全长AUREO 1a中J（alpha）螺旋或其他片段的信号传递进展。将研究推定的转录因子的DNA结合能力。来自三角褐指藻的其他金色素将异源表达，并且将分析它们的光化学性质关于它们在体内的作用。对这些金色素和隐花色素中新的信号传递途径的研究将大大拓宽我们目前对光传感器的理解。