Québec-Océan, Département de Biologie, and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada.
PLoS One. 2012;7(7):e40102. doi: 10.1371/journal.pone.0040102. Epub 2012 Jul 6.
Among dsDNA tailed bacteriophages (Caudovirales), members of the Myoviridae family have the most sophisticated virion design that includes a complex contractile tail structure. The Myoviridae generally have larger genomes than the other phage families. Relatively few "dwarf" myoviruses, those with a genome size of less than 50 kb such as those of the Mu group, have been analyzed in extenso. Here we report on the genome sequencing and morphological characterization of a new group of such phages that infect a diverse range of Proteobacteria, namely Aeromonas salmonicida phage 56, Vibrio cholerae phages 138 and CP-T1, Bdellovibrio phage φ1422, and Pectobacterium carotovorum phage ZF40. This group of dwarf myoviruses shares an identical virion morphology, characterized by usually short contractile tails, and have genome sizes of approximately 45 kb. Although their genome sequences are variable in their lysogeny, replication, and host adaption modules, presumably reflecting differing lifestyles and hosts, their structural and morphogenesis modules have been evolutionarily constrained by their virion morphology. Comparative genomic analysis reveals that these phages, along with related prophage genomes, form a new coherent group within the Myoviridae. The results presented in this communication support the hypothesis that the diversity of phages may be more structured than generally believed and that the innumerable phages in the biosphere all belong to discrete lineages or families.
在双链 DNA 长尾噬菌体（Caudovirales）中，肌尾噬菌体科（Myoviridae）的成员具有最复杂的病毒粒子设计，包括复杂的可收缩尾部结构。肌尾噬菌体科通常比其他噬菌体科具有更大的基因组。相对较少的“矮小”肌尾噬菌体，即基因组大小小于 50 kb 的噬菌体，如 Mu 群的噬菌体，已经被广泛分析。在这里，我们报告了一组新的感染多种变形杆菌的此类噬菌体的基因组测序和形态特征，即感染鲑鱼气单胞菌的噬菌体 56、霍乱弧菌噬菌体 138 和 CP-T1、噬菌蛭弧菌噬菌体 φ1422 和果胶杆菌噬菌体 ZF40。这组矮小肌尾噬菌体具有相同的病毒粒子形态特征，通常具有短的可收缩尾部，基因组大小约为 45 kb。尽管它们的基因组序列在溶原、复制和宿主适应模块中存在差异，可能反映了不同的生活方式和宿主，但它们的结构和形态发生模块受到其病毒粒子形态的进化限制。比较基因组分析表明，这些噬菌体以及相关的前噬菌体基因组，在肌尾噬菌体科内形成了一个新的连贯群体。本通讯中提出的结果支持这样一种假设，即噬菌体的多样性可能比普遍认为的更为结构化，而且生物圈中无数的噬菌体都属于离散的谱系或家族。
