Neutrality of foreign complex subunits in an experimental model of lateral gene transfer.
Neutrality of foreign complex subunits in an experimental model of lateral gene transfer.
复制标题
横向基因转移实验模型中外来复杂亚基的中性。
DOI：
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发表时间：
2008
影响因子：
10.7
通讯作者：
U. Gophna
中科院分区：
文献类型：
--
作者：
Alon Wellner;U. Gophna
横向基因转移(LGT)是微生物进化的一股强大力量。然而，限制这种进化现象的障碍还没有完全被理解。长期以来，人们一直观察到，编码复合体亚单位的基因表现出相对兼容的系统发育，这意味着大部分是垂直进化。这可能是因为一种新的基因产物未能与先前存在的蛋白质亚单位有效地相互作用，使其获得中立--这一理论被称为“复杂性假说”。另一方面，这些基因可能会通过扰乱复杂亚基之间的化学计量平衡来降低寄主的适合度，导致净化选择而不是基因保留。为了检验这两种替代方案，我们设计了一个实验系统，模拟将编码基本复杂亚基同源的基因转移到模式细菌大肠杆菌中。此外，我们过表达了天然的大肠杆菌基因，以检验基因剂量效应的贡献。我们表明，细胞中天然或外来复杂亚基的积累并不会导致适应度的丧失，除了观察到的单个外来同源物的轻微适应度降低。事实上，一系列的遗传和生化分析未能检测到外来亚基与复合体的天然多肽之间的任何相互作用，这意味着这种转移事件无法产生积极的基因保留选择。我们的结论是，复杂亚基的LGT可能大部分是中性的，反对基因保留的作用力似乎是适度的。
Lateral gene transfer (LGT) is a powerful force in microbial evolution. However, the barriers that restrict this evolutionary phenomenon are not fully understood. It has long been observed that genes that encode subunits of complexes exhibit relatively compatible phylogenies, implying mostly vertical evolution. This may be explained by the failure of a new gene product to effectively interact with preexisting protein subunits, making its acquisition neutral--a theory termed the "complexity hypothesis." On the other hand, such genes may reduce the fitness of the host by disturbing the stoichiometric balance between complex subunits, resulting in purifying selection against gene retention. To examine these 2 alternative scenarios, we designed an experimental system that mimics the transfer of genes encoding homologs of essential complex subunits into the model bacterium Escherichia coli. In addition, we overexpressed the native E. coli gene in order to examine the contribution of gene dosage effects. We show that accumulation of native or foreign complex subunits in the cell does not result in loss of fitness, except for a minor fitness reduction observed for a single foreign homolog. Indeed, a series of genetic and biochemical assays failed to detect any interaction between the foreign subunits and the native polypeptides of the complex, implying an inability of such transfer events to generate positive selection for gene retention. We conclude that LGT of complex subunits may be mostly neutral and that forces operating against gene retention appear to be moderate.
影响因子：
10.7
作者：
Novozhilov, AS;Karev, GP;Koonin, EV
通讯作者：
Koonin, EV