Comparative study of overlapping genes in the genomes of Mycoplasma genitalium and Mycoplasma pneumoniae
Comparative study of overlapping genes in the genomes of Mycoplasma genitalium and Mycoplasma pneumoniae
复制标题
DOI：
10.1093/nar/27.8.1847
复制
发表时间：
1999-04-15
影响因子：
14.9
通讯作者：
Tomita, M
中科院分区：
文献类型：
--
作者：
Fukuda, Y;Washio, T;Tomita, M
本文将重叠基因定义为一对编码区部分重叠的相邻基因。我们系统地分析了两个密切相关的物种：生殖支原体和肺炎支原体的基因组中的所有重叠基因。仔细比较了在一个物种中重叠但在另一个物种中不重叠的同源基因。这种比较分析使我们能够提出一个模型，说明重叠基因是如何在进化过程中出现的。发现重叠基因的产生主要是由于任一基因中终止密码子的丢失，在许多情况下，终止密码子的缺失导致基因编码区3'端的延长。更具体地说，终止密码子的丢失是由于以下事件发生的：终止密码子的缺失（64.4%）、终止密码子的点突变（4.4%）和编码区末端的移码（6.7%）。在某种意义上，重叠的基因可以被认为是进化压力的结果，以最小化基因组的大小。然而，我们的分析表明，许多重叠的基因，至少在生殖支原体和肺炎支原体的基因组中，是由于编码区的偶然延长。
Overlapping genes are defined, in this paper, as a pair of adjacent genes whose coding regions are partly overlapping. We systematically analyzed all overlapping genes in the genomes of two closely related species: Mycoplasma genitalium and Mycoplasma pneumoniae. Careful comparisons were made for homologous genes that are overlapped in one species but not in the other. This comparative analysis allows us to propose a model of how overlapping genes emerged in the course of evolution. It was found that overlapping genes were generated primarily due to the loss of a stop codon in either gene, in many cases, the absence of which resulted in elongation of the 3' end of the gene's coding region. More specifically, the loss of the stop codon took place as a result of the following events: deletion of the stop codon (64.4%), point mutation at the stop codon (4.4%), and frame shift at the end of the coding region (6.7%). Overlapping genes, in a sense, can be thought of as the results of evolutionary pressure to minimize genome size. However, our analysis indicates that many overlapping genes, at least in the genomes of M.genitalium and M.pneumoniae, are due to incidental elongation of the coding regions.