Comeau André M, Bertrand Claire, Letarov Andrei, Tétart Françoise, Krisch H M
Laboratoire de Microbiologie et Génétique Moléculaire, CNRS-UMR5100, 31062 Toulouse Cedex 9, France.
Virology. 2007 Jun 5;362(2):384-96. doi: 10.1016/j.virol.2006.12.031. Epub 2007 Feb 7.
Among the most numerous objects in the biosphere, phages show enormous diversity in morphology and genetic content. We have sequenced 7 T4-like phages and compared their genome architecture. All seven phages share a core genome with T4 that is interrupted by several hyperplastic regions (HPRs) where most of their divergence occurs. The core primarily includes homologues of essential T4 genes, such as the virion structure and DNA replication genes. In contrast, the HPRs contain mostly novel genes of unknown function and origin. A few of the HPR genes that can be assigned putative functions, such as a series of novel Internal Proteins, are implicated in phage adaptation to the host. Thus, the T4-like genome appears to be partitioned into discrete segments that fulfil different functions and behave differently in evolution. Such partitioning may be critical for these large and complex phages to maintain their flexibility, while simultaneously allowing them to conserve their highly successful virion design and mode of replication.
作为生物圈中数量最为庞大的物体之一，噬菌体在形态和基因内容上展现出了巨大的多样性。我们对7种T4样噬菌体进行了测序，并比较了它们的基因组结构。所有这7种噬菌体都与T4共享一个核心基因组，该核心基因组被几个增生区域（HPRs）打断，它们的大部分差异都出现在这些区域。核心主要包括T4必需基因的同源物，如病毒体结构和DNA复制基因。相比之下，HPRs大多包含功能和起源未知的新基因。少数几个可赋予推定功能的HPR基因，如一系列新的内部蛋白，与噬菌体对宿主的适应性有关。因此，T4样基因组似乎被划分成了不同的片段，这些片段履行不同的功能，并且在进化过程中表现各异。这种划分对于这些大型复杂噬菌体维持其灵活性可能至关重要，同时还能使它们保留极为成功的病毒体设计和复制模式。
