Light harvesting proteins in diatoms - functional heterogeneity and regulation

该项目的主要目的是更深入地研究新发现的，不寻常的隐色素CryP在羽状硅藻三角褐指藻中的作用。根据光谱分析，CryP具有DASH样特征，但在序列分析中也与植物Crys接近，显示其参与不同捕光蛋白（岩藻黄素叶绿素蛋白，FCPs）的总体蛋白质水平的调节。在这里，我们将专注于CryP对光捕获蛋白组织的影响。许多FCP在硅藻中表达，并且主要以三聚体形式组装，其在多肽组成上不同，并且在色素沉着上也略有不同。我们希望使用我们的CryP敲除系来进行生物化学测试，哪些FCP三聚体受到CryP作用的影响。由于CryP与植物Crys有关，因此这种影响是否与生物钟有关将在mRNA水平上确定。此外，还应阐明CryP的细胞定位。由于CryP的光谱特征类似于DASH蛋白，因此也将测试其可能的双功能性，即参与DNA修复。光谱和结构的蛋白质连同mRNA的定量研究在不同的光条件下应提供进一步的洞察的作用模式，以及可能的相互作用的合作伙伴的识别。

The major aim of the project is to examine more deeply the effects of the newly identified, unusual cryptochrome CryP in the pennate diatom Phaeodactylum tricornutum. CryP, having DASH like features according to spectroscopic analyses but also grouping close to plant Crys in sequence analyses, was shown to be involved in the regulation of the overall protein levels of different light-harvesting proteins (fucoxanthin chlorophyll proteins, FCPs). Here, we will focus on the influence of CryP on the organisation of light harvesting proteins. Many FCPs are expressed in diatoms and assemble mostly in trimers, which differ in polypeptide composition and also slightly in pigmentation. We want to use our CryP knockdown lines to test biochemically, which FCP trimers are influenced by the action of CryP. Whether this influence is in relation to the circadian clock will be determined on mRNA level, since CryP is related to plant Crys. In addition, the cellular localization of CryP should be clarified. Since the spectroscopic features of CryP resemble CRY-DASH proteins, its possible bi-functionality, i.e. an involvement in DNA repair, will be tested as well. Spectroscopic and structural investigations on the protein together with mRNA quantifications under different light conditions should provide further insight into the mode of action, as well as the identification of possible interaction partners.