Polar freshwater cyanophage S-EIV1 represents a new widespread evolutionary lineage of phages
Polar freshwater cyanophage S-EIV1 represents a new widespread evolutionary lineage of phages
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DOI：
10.1038/ismej.2015.24
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发表时间：
2015-09-01
期刊：
影响因子：
11
通讯作者：
Suttle, C. A.
中科院分区：
文献类型：
--
作者：
Chenard, C.;Chan, A. M.;Suttle, C. A.
蓝藻通常是极地淡水群落中的主要光养生物；然而，感染它们的噬菌体仍不清楚。在这里，我们对从埃尔斯米尔岛(加拿大高北极努纳武特)淡水中分离到的侵染极地聚球藻PCCC-A2c菌株的噬藻体S-EIV1进行了基因组和形态特征分析。S-EIV1代表了一个新发现的噬菌体进化谱系，其代表广泛存在于水生系统中。在预测的130个开放阅读框(ORF)中，除了大末端亚基和一个遥远的病毒形态发生蛋白外，没有发现与编码结构蛋白的基因相似，这表明编码S病毒结构蛋白的基因与其他病毒不同。此外，在79 178个碱基的循环排列的基因组上，只有19个预测的编码序列与编码已知功能的蛋白质的基因有同源性。虽然S-EIV1与其他已测序的噬菌体分离株不同，但它与地中海深叶绿素最高值区的融合蛋白上捕获的噬菌体基因以及可变鱼腥藻(ATCC 29413)基因组中的一个切割元件具有同源性。元基因组数据的序列募集表明，S类病毒具有世界性，并在广泛的水生系统中大量存在，表明它们具有重要的生态作用。
Cyanobacteria are often the dominant phototrophs in polar freshwater communities; yet, the phages that infect them remain unknown. Here, we present a genomic and morphological characterization of cyanophage S-EIV1 that was isolated from freshwaters on Ellesmere Island (Nunavut, High Arctic Canada), and which infects the polar Synechococcus sp., strain PCCC-A2c. S-EIV1 represents a newly discovered evolutionary lineage of bacteriophages whose representatives are widespread in aquatic systems. Among the 130 predicted open reading frames (ORFs) there is no recognizable similarity to genes that encode structural proteins other than the large terminase subunit and a distant viral morphogenesis protein, indicating that the genes encoding the structural proteins of S-EIV1 are distinct from other viruses. As well, only 19 predicted coding sequences on the 79 178 bp circularly permuted genome have homology with genes encoding proteins of known function. Although S-EIV1 is divergent from other sequenced phage isolates, it shares synteny with phage genes captured on a fosmid from the deep-chlorophyll maximum in the Mediterranean Sea, as well as with an incision element in the genome of Anabaena variabilis (ATCC 29413). Sequence recruitment of metagenomic data indicates that S-EIV1-like viruses are cosmopolitan and abundant in a wide range of aquatic systems, suggesting they have an important ecological role.