Department of Biology, Memorial University of Newfoundland, St. John's, A1B 3X9, Canada; email:
Department of Microbiology and Immunology, University of British Columbia, Vancouver, V6T 1Z3, Canada.
Annu Rev Virol. 2017 Sep 29;4(1):87-104. doi: 10.1146/annurev-virology-101416-041624. Epub 2017 Aug 7.
Diverse prokaryotes produce gene transfer agents (GTAs), which are bacteriophage-like particles that exclusively package pieces of the producing cell's genome and transfer them to other cells. There are clear evolutionary connections between GTAs and phages, but GTAs have properties that lead us to suggest they are more than simply defective phages and instead provide a selective advantage for the producing organisms. The five types of currently known GTAs are genetically distinct, indicating multiple instances of convergent evolution. GTA production can be regulated by the producing organism and coordinated to coincide with development of the capability to receive DNA from GTAs. Recent discoveries of the genetic basis of GTA production in the bacterium Rhodobacter capsulatus and characterization of novel phages that possess homologs of this GTA's structural and regulatory genes have provided important new connections among these elements and highlight the tangled evolutionary relationships within the phageome.
多样的原核生物产生基因转移因子（GTAs），这是一种类似噬菌体的颗粒，专门包装产生细胞基因组的片段，并将其转移到其他细胞中。GTAs 和噬菌体之间存在明显的进化联系，但 GTAs 具有一些特性，使我们认为它们不仅仅是缺陷噬菌体，而是为产生它们的生物体提供了选择性优势。目前已知的五种类型的 GTA 在基因上是不同的，这表明它们经历了多次趋同进化。GTA 的产生可以被产生它们的生物体调控，并与从 GTAs 接收 DNA 的能力的发展相协调。最近在细菌 Rhodobacter capsulatus 中发现了 GTA 产生的遗传基础，并对具有该 GTA 结构和调节基因同源物的新型噬菌体进行了描述，这些发现为这些要素之间提供了重要的新联系，并突出了噬菌体组内复杂的进化关系。
