Spontaneous Deletion of an "ORFanage" Region Facilitates Host Adaptation in a "Photosynthetic" Cyanophage.
Spontaneous Deletion of an "ORFanage" Region Facilitates Host Adaptation in a "Photosynthetic" Cyanophage.
复制标题
DOI：
10.1371/journal.pone.0132642
复制
发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Scanlan DJ
中科院分区：
文献类型：
--
作者：
Puxty RJ;Perez-Sepulveda B;Rihtman B;Evans DJ;Millard AD;Scanlan DJ
病毒被认为是地球上遗传多样性的最大来源。基因组测序和宏基因组学研究表明，病毒基因组中存在大量功能未知的新基因。然而，对于这些基因获得和丢失的过程和频率，几乎没有观察。海洋环境的表面沃茨主要由海洋微蓝细菌及其共存的病毒（噬藻体）。最近的噬藻体基因组测序揭示了大量的基因，已获得从他们的蓝藻宿主。在这里，我们重新测序噬藻体S-PM2基因组经过10年的近连续通过其海洋聚球藻宿主。在此期间，缺乏13%的S-PM2 ORF的自发突变体（S-PM 2d）在噬藻体群体中占主导地位。这些ORF位于一个基因座上，并且与任何其他测序生物体（ORFans）中的任何蛋白质都不同源。我们证明了健身成本S-PM2 WT拥有这些ORF下标准的实验室生长。宏基因组学调查显示，这些ORF存在于各种水生环境中，可能是噬藻体起源，并且似乎在极端盐度（淡水和高盐）的环境中富集。我们认为，这些ORF有助于灵活的基因内容的噬藻体，并提供了一个独特的健身优势，在淡水和高盐环境。
Viruses have been suggested to be the largest source of genetic diversity on Earth. Genome sequencing and metagenomic surveys reveal that novel genes with unknown functions are abundant in viral genomes. Yet few observations exist for the processes and frequency by which these genes are gained and lost. The surface waters of marine environments are dominated by marine picocyanobacteria and their co-existing viruses (cyanophages). Recent genome sequencing of cyanophages has revealed a vast array of genes that have been acquired from their cyanobacterial hosts. Here, we re-sequenced the cyanophage S-PM2 genome after 10 years of near continuous passage through its marine Synechococcus host. During this time a spontaneous mutant (S-PM2d) lacking 13% of the S-PM2 ORFs became dominant in the cyanophage population. These ORFs are found at one loci and are not homologous to any proteins in any other sequenced organism (ORFans). We demonstrate a fitness cost to S-PM2WT associated with possession of these ORFs under standard laboratory growth. Metagenomic surveys reveal these ORFs are present in various aquatic environments, are likely of cyanophage origin and appear to be enriched in environments from the extremes of salinity (freshwater and hypersaline). We posit that these ORFs contribute to the flexible gene content of cyanophages and offer a distinct fitness advantage in freshwater and hypersaline environments.