Central Project

光对藻类有重要的影响：(1)作为光合作用的能源；(2)通过光感受器触发由光感知介导的行为反应；(3)通过光-暗循环调节它们的生物钟。联合基因组研究所(美国能源部)最近对绿藻衣藻和硅藻三角褐指藻的基因组进行了测序，并进行了国际注释工作，以便进行比较基因组方法以及蛋白质组分析，例如对衣藻的眼点装置进行分析，衣藻是一种原始的视觉系统。除了基因组和蛋白质组方法，在过去的几年里，国际上已经为这两种藻类开发了几种分子遗传学工具。总之，这些努力提供了新的信息，并代表了一个有效的平台，以执行深入表征涉及光驱动途径的相关蛋白质。这种努力需要在生理学、分子生物学和/或生物物理学方面有经验的科学家合作。在这个研究小组的框架内，我们组建了一个这样一个跨学科的团队，希望专注于光驱动反应的新方面，从光吸收到生理反应，这些反应对这两个物种中的任何一个都是典型的，而且关于这一过程的深刻信息仍然缺乏或非常有限。其中一个重点将放在涉及光和昼夜节律信号的莱茵哈迪尔毛虫光感受器的功能和生物物理特征上。生理学研究表明，蓝光与携带衣藻生物钟有关。潜在的候选者是植物和动物样的隐色素、通道视紫红质2和趋光素。另一个焦点将是莱茵梭菌中的光信号级联，涉及位于眼点装置中的通道视紫红质和钙结合蛋白，这些蛋白可以调节吸收的光信息。因此，在眼斑蛋白质组中也发现的灵魂血红素结合蛋白(SOUL3)将进一步引起人们的兴趣。SOURE首先在脊椎动物中被描述，其mRNA在视网膜和松果体中特异表达(Zylka和Reppert，1999)。此外，含有组氨酸激酶和反应调节结构域的类似酶的视紫红质，其功能到目前为止完全未知，将在研究中。在三角硅藻中，我们将首次分析隐色素的功能以及硅藻金色蛋白的功能。我们的研究还将包括在不同水平上理解硅藻光合作用的光调节机制，即相关蛋白质的光依赖合成，以及氧化还原介导的调节过程。尽管硅藻对地球初级生产力的贡献高达20%，但与绿色血统相比，人们对它们的光合作用知之甚少。这种结合的跨学科方法将给出从光的吸收到所涉及的信号级联成员的功能的具体光驱动反应的详细视图，以及它们在两个所选模型藻中不同生物过程中的相关性。

Light has major impacts on algae (i) serving as energy source for photosynthesis, (ii) triggering behavioral responses mediated by light perception via photoreceptors and (iii) entraining their circadian clocks by light-dark cycles. The recent sequencing of the genomes of the green alga Chlamydomonas reinhardtii and of the diatom Phaeodactylum tricornutum by the Joint Genome Institute (JGIDepartment of Energy, USA) and the international annotation effort allowed to perform comparative genome approaches as well as proteomic analysis, e.g. of the eyespot apparatus of Chlamydomonas, a primordial visual system. Along with the genome and proteome approaches, several molecular genetic tools have been developed on an international basis in the past years for these two algae. Altogether, these efforts provide novel information and represent an efficient platform to perform an in-depth characterization of relevant proteins involved in lightdriven pathways. Such an effort requires the collaboration of scientists who are experienced in physiology, molecular biology and/or biophysics. Within the Frame of this research group, we have assembled such an interdisciplinary team and want to focus on novel aspects of light-driven reactions from light absorption to physiological responses that are typical for either of the two species and where profound information about the processes is still lacking or is very limited. One focus will be on the functional and biophysical characterization of photoreceptors in C. reinhardtii that are involved in light- and circadian signaling. Blue light has been shown by physiological studies to be relevant for entraining the clock of Chlamydomonas. Potential candidates are plant- and animal-like cryptochromes, channelrhodopsin 2 and phototropin. Another focus will be on the light-signalingcascade in C. reinhardtii involving channelrhodopsins and Ca2+-binding Proteins located in the eyespot apparatus that can mediate absorbed light information. Thereby, a SOUL heme-binding protein (SOUL3) that was also found in the eyespot proteome will be of further interest. SOUL was first described in vertebrates where its mRNA is specifically expressed in the retina and pineal gland (Zylka and Reppert, 1999). Moreover, enzyme-like rhodopsins containing His-kinase and response regulator domains, whose function is completely unknown so far, will be under investigation. In the diatom P. tricornutum, we will analyze for the first time the function of the cryptochromes as well as of the diatom aureochromes. Our studies will also include an understanding of the mechanism of the light Regulation of diatom photosynthesis on different levels, i.e. the light-dependent synthesis of relevant proteins, as well as redox mediated regulation processes. Albeit diatoms contribute up to 20% to the primary production on Earth, little is known about their photosynthesis in comparison to the green lineage. This combined interdisciplinary approach will give a detailed view about specific light-driven reactions from the absorption of light to the function of the involved signaling cascade members and their relevance in different biological processes in the two chosen model algae.