Cryptochrome photoreceptors in the green alga Chlamydomonas reinhardtii: Versatility of functions and mechanisms

微藻生活在海洋、淡水和/或潮湿的土壤中。它们对全球碳固定做出了重大贡献，是食物网的基础。为了应对水柱中不同强度和质量的光，他们开发了各种具有新功能和机制的光感受器。几十年来，双鞭毛绿色单细胞藻类莱茵衣藻一直被用作研究光驱动过程的模型，因为它可以被转化，并且可以与面包酵母进行遗传杂交。光影响它的行为，它的生命周期，光合作用，并通过光暗循环同步它的生物钟。瓢虫有18种不同的光感受器，其中一些我们不知道任何功能或作用机制。这些受体中有四种属于来自DNA修复酶（光解酶）的隐花色素（CRY）家族，包括在高等植物中发现的典型植物CRY (pCRY)，动物类CRY （aCRY）以及两种dash类CRYs。在本文中，我们旨在进一步研究绿藻隐色素的功能和机制。我们感兴趣的是(a)藻类性周期中aCRY的降解机制及其对生命周期的影响，(b)夜间pCRY的相互作用伙伴及其对昼夜节律和/或生命周期调节的贡献，以及(c)两个CRY-DASHs仍然难以捉摸的作用的功能。插入敲除和已知突变体可用于此目的，CRISPR/Cas9方法可用于产生进一步的突变体。我们想要了解各种隐花色素光感受器及其不同的吸收光谱如何控制藻类的生命，并旨在揭示不同隐花色素的重叠和不同的功能。

Microalgae live in the ocean, freshwater and/or wet soil. They contribute significantly to global carbon fixation and are at the basis of food webs. To cope with the different intensities and qualities of light in the water column, they developed a large variety of photoreceptors with novel functions and mechanisms. The biflagellate green unicellular alga Chlamydomonas reinhardtii serves since decades as a model to study light-driven processes, since it can be transformed and genetic crosses are possible such as with baker’s yeast. Light influences its behavior, its life cycle, photosynthesis and synchronizes its circadian clock by light-dark cycles. C. reinhardtii has 18 different putative photoreceptors and from some of them we do not know any function or mechanism of action. Four of these receptors belong to the cryptochrome (CRY) family that derives from DNA repair enzymes (photolyases), including a typical plant CRY (pCRY) as found in higher plants, an animal-like CRY (aCRY) as well as two DASH-like CRYs. In this proposal, we aim to study further the functions and mechanisms of the green algal cryptochromes. We are interested in (a) the mechanism of degradation of aCRY during the sexual cycle of the alga and its influence on the life cycle as well as in (b) the interaction partner(s) of pCRY in the night and their contribution to circadian and/or life cycle regulation as well as in (c) the functions of the still elusive roles of the two CRY-DASHs. Insertional knock-down and know out mutants are available for this purpose and CRISPR/Cas9 approaches can be used for generating further mutants. We want to understand how the variety of cryptochrome photoreceptors along with their different absorption spectra controls algal life and aim to reveal the overlapping as well as the distinct functions of the different cryptochromes.