Cyanophages, widespread in aquatic systems, are a class of viruses that specifically infect cyanobacteria. Though they play important roles in modulating the homeostasis of cyanobacterial populations, little is known about the freshwater cyanophages, especially those hypothetical proteins of unknown function. Mic1 is a freshwater siphocyanophage isolated from the Lake Chaohu. It encodes three hypothetical proteins Gp65, Gp66, and Gp72, which share an identity of 61.6% to 83%. However, we find these three homologous proteins differ from each other in oligomeric state. Moreover, we solve the crystal structure of Gp72 at 2.3 Å, which represents a novel fold in the α + β class. Structural analyses combined with redox assays enable us to propose a model of disulfide bond mediated oligomerization for Gp72. Altogether, these findings provide structural and biochemical basis for further investigations on the freshwater cyanophage Mic1.

中文翻译：

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淡水蓝藻Mic1的新型折叠蛋白Gp72的晶体结构。

蓝藻在水生系统中广泛分布，是一类特异性感染蓝细菌的病毒。尽管它们在调节蓝细菌种群的稳态中起着重要作用，但对淡水蓝藻的了解却很少，尤其是那些功能未知的假想蛋白质。Mic1是从巢湖中分离出的淡水蓝藻。它编码三种假设的蛋白Gp65，Gp66和Gp72，它们的同一性为61.6％至83％。然而，我们发现这三种同源蛋白在寡聚状态上彼此不同。此外，我们将Gp72的晶体结构解析为2.3，这代表了α+β类的新折叠。结构分析与氧化还原分析相结合，使我们能够提出Gp72的二硫键介导的寡聚化模型。共，