Natural functions of CRISPR-Cas systems in Cyanobacteria

阳光是地球上生命的普遍能源。即使是不吸收光来产生能量的生物体，基本上也要依靠光合作用产生的氧气和生物量。蓝藻在所有水生环境中都是非常丰富的生物，但在陆地栖息地也经常发现。此外，光合生物将固定的二氧化碳转化为不同的可用碳基产品，这使得它们对生物技术非常有吸引力。然而，在其自然栖息地以及生产设施中，蓝藻可以被噬藻体感染。与许多其他细菌和古细菌类似，它们已经发展出防御系统来保护自己免受外来核酸的入侵。在这个项目中，我们将通过测试CRISPR依赖的基因调控，核糖核酸酶在这一过程中的作用，以及不同CRISPR相关蛋白的定位和蛋白-蛋白相互作用研究，来研究基于CRISPR的防御系统与其他细胞功能之间的联系。此外，我们将测试蓝藻CRISPR-Cas III-B系统能够合成第二信使核苷酸的假设，并分析这种假设的信号系统的机制和生理意义。

Sunlight is the universal energy source for life on Earth. Even organisms that do not absorb light for energy production essentially depend on photosynthetically produced oxygen and biomass. Cyanobacteria are very abundant organisms in all aquatic environments, but are often found also in terrestrial habitats. In addition, photosynthetic organisms convert fixed carbon dioxide into different useable carbon-based products what makes them very attractive for biotechnology. However, cyanobacteria can be infected by cyanophages in their natural habitat as well as in production facilities. Similar to many other bacteria and Archaea they have developed defence systems to protect themselves against invasion by foreign nucleic acids. In this programme, we will investigate the interconnection between the CRISPR-based defence system and other cellular functions by testing CRISPR-dependent gene regulation, the role of ribonucleases in this process and by localization and protein-protein interaction studies of different CRISPR associated proteins. In addition, we will test the hypothesis that the cyanobacterial CRISPR-Cas III-B system is able to synthesize second messenger nucleotides and will analyse the mechanism and physiological meaning of such a putative signalling system.