Lefeuvre Pierre, Lett Jean-Michel, Reynaud Bernard, Martin Darren P
CIRAD, UMR 53 PVBMT CIRAD-Université de la Réunion, Pô le de Protection des Plantes, Ligne Paradis, Saint Pierre, La Réunion, France.
PLoS Pathog. 2007 Nov;3(11):e181. doi: 10.1371/journal.ppat.0030181.
With the development of reliable recombination detection tools and an increasing number of available genome sequences, many studies have reported evidence of recombination in a wide range of virus genera. Recombination is apparently a major mechanism in virus evolution, allowing viruses to evolve more quickly by providing immediate direct access to many more areas of a sequence space than are accessible by mutation alone. Recombination has been widely described amongst the insect-transmitted plant viruses in the genus Begomovirus (family Geminiviridae), with potential recombination hot- and cold-spots also having been identified. Nevertheless, because very little is understood about either the biochemical predispositions of different genomic regions to recombine or what makes some recombinants more viable than others, the sources of the evolutionary and biochemical forces shaping distinctive recombination patterns observed in nature remain obscure. Here we present a detailed analysis of unique recombination events detectable in the DNA-A and DNA-A-like genome components of bipartite and monopartite begomoviruses. We demonstrate both that recombination breakpoint hot- and cold-spots are conserved between the two groups of viruses, and that patterns of sequence exchange amongst the genomes are obviously non-random. Using a computational technique designed to predict structural perturbations in chimaeric proteins, we demonstrate that observed recombination events tend to be less disruptive than sets of simulated ones. Purifying selection acting against natural recombinants expressing improperly folded chimaeric proteins is therefore a major determinant of natural recombination patterns in begomoviruses.
随着可靠的重组检测工具的发展以及可用基因组序列数量的增加,许多研究报告了多种病毒属中存在重组的证据。重组显然是病毒进化中的一种主要机制,它使病毒能够通过直接获取比仅靠突变所能触及的更多的序列空间区域,从而更快地进化。在双生病毒科菜豆金色花叶病毒属中由昆虫传播的植物病毒之间,重组现象已被广泛描述,并且还确定了潜在的重组热点和冷点。然而,由于对于不同基因组区域重组的生化倾向以及为何某些重组体比其他重组体更具生存能力了解甚少,塑造自然界中观察到的独特重组模式的进化和生化力量的来源仍然不明。在此,我们对双分体和单分体菜豆金色花叶病毒的DNA-A和类DNA-A基因组组件中可检测到的独特重组事件进行了详细分析。我们证明,这两组病毒之间的重组断点热点和冷点是保守的,并且基因组之间的序列交换模式明显是非随机的。使用一种旨在预测嵌合蛋白结构扰动的计算技术,我们证明观察到的重组事件往往比模拟的重组事件集破坏性更小。因此,针对表达折叠不当的嵌合蛋白的天然重组体的纯化选择是菜豆金色花叶病毒天然重组模式的主要决定因素。