果蝇基因组中回文序列的分布

Palindrome Distribution in the Fly Genome

回文序列(palindrome)是与基因表达调控、DNA复制和重组密切相关的重要DNA模体。例如,回文序列常存在于基因表达顺式作用元件中,参与基因表达调控;回文序列也可作为限制性内切酶的识别位点或结构信号,诱导重组的发生,而重组作为选择的途径,反过来可能会调节回文序列在染色体上的分布。在全基因组范围内研究回文序列的分布及其与染色体重组的关系,对从分子水平上理解基因表达调控机制及基因组进化有重要意义。本文对果蝇基因组回文序列在染色体上的分布进行了系统的分析,发现果蝇基因组对回文序列的使用是非随机的,回文序列在染色体上的分布受到重组率、基因分布和GC含量等因素的影响。回文序列丰度、回文密度与重组率的关系,以及回文序列GC含量与重组率的关系在常染色体和X染色体上的巨大反差,预示着常染色体和X染色体在功能及进化上的某些根本性差异可能与回文序列有关。

Palindromic sequences are important DNA motifs relating to the gene regulation,DNA replication and recombinaton.For example,panlindromes are often found in various cis-acting genetic elements.Palindromes can also provoke DNA recombination inducing DNA double strand breaks as it serves as recognition sites or structural signal for restriction enzymes.Genome-wide study of the distribution of palindromes along chromosomes and its link to recombination would shed light on the molecular mechanism of gene regulation and genome evolution.In this study,the genomic distribution of palindromes in Drosophila melanogaster genome is systematically analyzed.The results show that the usage of palindromes in the fly genome is non-random,and the genomic distribution of palindromes is associated with recombination rate,gene density and GC content.Palindrome abundance,the correlation between palindrome distribution and recombination rate,and the correlation between palindrome GC content and recombination rate differ significantly beween autosomes and X chromosome,suggesting the difference in function and evolution between autosomes and X chromosome is likely to be associated with palindromes.