The mitochondrial genome of the lizard Calotes versicolor and a novel gene inversion in south Asian draconine agamids
The mitochondrial genome of the lizard Calotes versicolor and a novel gene inversion in south Asian draconine agamids
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DOI：
10.1093/molbev/msm054
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发表时间：
2007-06-01
影响因子：
10.7
通讯作者：
Kumazawa, Yoshinori
中科院分区：
文献类型：
--
作者：
Amer, Sayed A. M.;Kumazawa, Yoshinori
一个完整的线粒体DNA（mtDNA）序列测定的蜥蜴Calotesversicolor（爬行纲; Agamidae）。16，670-bp的基因组与一些蛋白质编码和tRNA基因的显着较短的基因具有与其他脊椎动物中发现的相同的基因内容。然而，一种新的基因排列被发现，其中脯氨酸tRNA（traditional）基因位于轻链，而不是其典型的重链位置，提供了第一个已知的例子，基因倒位在脊椎动物mtDNA。一段线粒体DNA包括traponin基因及其侧翼基因和控制区的扩增和测序的各种agamid类群调查的时间和机制的基因倒位。所有南亚龙蒿碱无鞭毛纲动物都有倒traponine基因组织，但没有其他亚洲和非洲无鞭毛纲动物。系统发育分析，包括无时钟贝叶斯分析的分歧时间估计表明，一个单一的发生的基因倒位的血统，导致在古近纪时期的龙血竭无鞭毛。这种基因倒位不能用线粒体基因重排的串联重复/随机丢失模型来解释。我们现有的序列数据并没有提供证据，在一个重复的tRNA基因的反密码子开关重塑的trypsin基因。基于序列比较和其他间接证据的结果，我们假设，倒位的tradoxin基因最初介导的同源DNA重组和从头基因组织，不破坏线粒体基因的表达已被保持在龙血竭mtDNA这么长的一段时间。
A complete mitochondrial DNA (mtDNA) sequence was determined for the lizard Calotes versicolor (Reptilia; Agamidae). The 16,670-bp genome with notable shorter genes for some protein-coding and tRNA genes had the same gene content as that found in other vertebrates. However, a novel gene arrangement was found in which the proline tRNA (trnP) gene is located in the light strand instead of its typical heavy-strand position, providing the first known example of gene inversion in vertebrate mtDNAs. A segment of mtDNA encompassing the trnP gene and its flanking genes and the control region was amplified and sequenced for various agamid taxa to investigate timing and mechanism of the gene inversion. The inverted trnP gene organization was shared by all South Asian draconine agamids examined but by none of the other Asian and African agamids. Phylogenetic analyses including clock-free Bayesian analyses for divergence time estimation suggested a single occurrence of the gene inversion on a lineage leading to the draconine agamids during the Paleogene period. This gene inversion could not be explained by the tandem duplication/random loss model for mitochondrial gene rearrangements. Our available sequence data did not provide evidence for remolding of the trnP gene by an anticodon switch in a duplicated tRNA gene. Based on results of sequence comparisons and other circumstantial evidence, we hypothesize that inversion of the trnP gene was originally mediated by a homologous DNA recombination and that the de novo gene organization that does not disrupt expression of mitochondrial genes has been maintained in draconine mtDNAs for such a long period of time.