Cazares Adrián, Mendoza-Hernández Guillermo, Guarneros Gabriel
Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV IPN), Mexico City, Mexico.
BMC Genomics. 2014 Dec 19;15(1):1146. doi: 10.1186/1471-2164-15-1146.
Bacteriophages that infect the opportunistic pathogen Pseudomonas aeruginosa have been classified into several groups. One of them, which includes temperate phage particles with icosahedral heads and long flexible tails, bears genomes whose architecture and replication mechanism, but not their nucleotide sequences, are like those of coliphage Mu. By comparing the genomic sequences of this group of P. aeruginosa phages one could draw conclusions about their ontogeny and evolution.
Two newly isolated Mu-like phages of P. aeruginosa are described and their genomes sequenced and compared with those available in the public data banks. The genome sequences of the two phages are similar to each other and to those of a group of P. aeruginosa transposable phages. Comparing twelve of these genomes revealed a common genomic architecture in the group. Each phage genome had numerous genes with homologues in all the other genomes and a set of variable genes specific for each genome. The first group, which comprised most of the genes with assigned functions, was named "core genome", and the second group, containing mostly short ORFs without assigned functions was called "accessory genome". Like in other phage groups, variable genes are confined to specific regions in the genome.
Based on the known and inferred functions for some of the variable genes of the phages analyzed here, they appear to confer selective advantages for the phage survival under particular host conditions. We speculate that phages have developed a mechanism for horizontally acquiring genes to incorporate them at specific loci in the genome that help phage adaptation to the selective pressures imposed by the host.
感染机会致病菌铜绿假单胞菌的噬菌体已被分为几个组。其中一组包括具有二十面体头部和长而灵活尾部的温和噬菌体颗粒，其基因组的结构和复制机制与大肠杆菌噬菌体Mu相似，但核苷酸序列不同。通过比较这组铜绿假单胞菌噬菌体的基因组序列，可以得出关于它们的个体发育和进化的结论。
描述了两种新分离的铜绿假单胞菌的类Mu噬菌体，并对其基因组进行了测序，并与公共数据库中可用的基因组进行了比较。这两种噬菌体的基因组序列彼此相似，并且与一组铜绿假单胞菌转座噬菌体的基因组序列相似。比较其中12个基因组揭示了该组中常见的基因组结构。每个噬菌体基因组都有许多在所有其他基因组中具有同源物的基因，以及一组每个基因组特有的可变基因。第一组包含大多数具有指定功能的基因，被命名为“核心基因组”，第二组主要包含没有指定功能的短开放阅读框，被称为“辅助基因组”。与其他噬菌体组一样，可变基因局限于基因组中的特定区域。
基于此处分析的噬菌体一些可变基因的已知和推断功能，它们似乎赋予噬菌体在特定宿主条件下生存的选择优势。我们推测噬菌体已经发展出一种水平获取基因的机制，以便将它们整合到基因组中的特定位点，这有助于噬菌体适应宿主施加的选择压力。
