内共生学说认为线粒体基因序列一定被成功地融合到核基因组中以维持真核细胞的代谢。但是插入事件的发生通常带来有害的影响,导致一些由于线粒体基因拷贝产生的疾病。除此之外,新的遗传物质的融合可能破坏合适的翻译系统。由此可见,相对很少的融合事件的发生才能产生重要的功能性的影响。线粒体基因的插入对增加基因组的复杂性是很重要的,有研究报道表明人类基因组中包含1000个编码线粒体蛋白的基因,超过90%的线粒体蛋白是核基因所编码的。
然而,线粒体基因的空间如何分布,从线粒体DNA中来的假基因在基因组中又是如何的定位的,我们都不是很清楚。首尔国立大学农业生物技术系的Sunjin Moon等人研究认为线粒体假基因的定位表明了进化的一个轨迹,好比一个分子化石。他们利用基于概率的方法和自举的方法估计参数阈值,这个参数阈值能很好地描述线粒体基因在核基因组中的分布情况。结果分析得到几乎一半的线粒体基因定位在染色体的着丝粒和亚着丝粒区域。巧合的是这些基因簇的大小从0.085 Mb到3.2Mb,恰好与进化区域的平均大小相一致,他们认为人类基因组中线粒体基因的定位倾向于独立的。相关论文发表在爱思唯尔期刊《基因组学》(Genomics)上。(生物谷Bioon.com)
生物谷推荐原始出处:
Genomics,Volume 92, Issue 2, August 2008, Pages 85-93,Sunjin Moon,Heebal Kim
Organization and evolution of mitochondrial gene clusters in human
Sunjin Moona, Seoae Chob and Heebal Kima, b, ,
aLaboratory of Bioinformatics and Population Genetics, Department of Agricultural Biotechnology, Seoul National University, Seoul 151-742, Korea
bGraduate Program in Bioinformatics, Seoul National University, Seoul 151-742, Korea
Currently, the spatial patterns of mitochondrial genes and how the genomic localization of (pseudo)genes originated from mitochondrial DNA remain largely unexplained. The aim of this study was to elucidate the organization of mitochondrial (pseudo)genes given their evolutionary origin. We used a keyword finding method and a bootstrapping method to estimate parameter values that represent the distribution pattern of mitochondrial genes in the nuclear genome. Almost half of mitochondrial genes showing physical clusters were located in the pericentromeric and subtelomeric regions of the chromosome. Most interestingly, the size of these clusters ranged from 0.085 to 3.2 Mb (average ± SD 1.3 ± 0.73 Mb), which coincides with the size of the evolutionary pocket, or the average size of evolutionary breakpoint regions. Our findings imply that the localization of mitochondrial genes in the human genome is determined independent of adaptation.