Distinct frequency-distributions of homopolymeric DNA tracts in different genomes
Distinct frequency-distributions of homopolymeric DNA tracts in different genomes
复制标题
DOI：
10.1093/nar/26.17.4056
复制
发表时间：
1998-09-01
影响因子：
14.9
通讯作者：
Leunissen, JAM
中科院分区：
文献类型：
--
作者：
Dechering, KJ;Cuelenaere, K;Leunissen, JAM
人类恶性疟原虫基因组的不寻常的碱基组成促使我们系统地研究恶性疟原虫基因组中均聚DNA片段的发生，并与智人、酿酒酵母、秀丽隐杆线虫、拟南芥、大肠杆菌和结核分枝杆菌的基因组进行比较。所观察到的频率与随机DNA的预期频率的比较表明，均聚（dA：dT）道发生在真核基因组中的机会。在大多数这些基因组中，（dA：dT）道过度表现被证明是一个指数函数的道长度。(dG：dC）道的过度表达在原核和真核基因组中均不存在或不太明显，在我们的研究结果的基础上，我们提出，均聚物（dA：dT）道通过复制滑动而扩展。这种滑动介导的扩展不操作的大片长度低于7-10 bp的临界阈值。
The unusual base composition of the genome of the human malaria parasite Plasmodium falciparum prompted us to systematically investigate the occurrence of homopolymeric DNA tracts in the P. falciparum genome and, for comparison, in the genomes of Homo sapiens, Saccharomyces cerevisiae, Caenorhabditis elegans, Arabidopsis thaliana, Escherichia coli and Mycobacterium tuberculosis. Comparison of the observed frequencies with the frequencies as expected for random DNA revealed that homopolymeric (dA:dT) tracts occur well above chance in the eukaryotic genome. In the majority of these genomes, (dA:dT) tract overrepresentation proved to be an exponential function of the tract length. (dG:dC) tract overrepresentation was absent or less pronounced in both prokaryotic and eukaryotic genomes, On the basis of our results, we propose that homopolymeric (dA:dT) tracts are expanded via replication slippage. This slippage-mediated expansion does not operate on tracts with lengths below a critical threshold of 7-10 bp.