DNA双链密码对使用的不对称性  

Asymmetry of Codon-pair Usage between DNA Double Strands

作　　者：王芳平[1] 李宏 王志坚[1] 

机构地区：[1]天水师范学院物理与信息科学学院物理系,甘肃天水741001 [2]内蒙古大学物理科学与技术学院,内蒙古呼和浩特010021

出　　处：《生物技术》2010年第4期14-18,共5页Biotechnology

基　　金：国家自然科学基金项目(30660044)资助

摘　　要：目的:分析基因组组分极其偏向的厌氧性粘菌和立克次氏体基因中密码对的使用,研究DNA双链密码对使用的不对称性。方法:生物统计学。结果:发现脱卤厌氧粘菌和立克次氏体基因组中分别有17%和21%的密码对在DNA双链上的使用偏好性正好相对,这表明它们的前导链与滞后链上密码对的使用偏好存在差异。因此,影响密码对搭配的重要原因之一是基因所在链的特性。这些特性可能包括:基因方向性偏好、密码子使用偏好、密码子的前后文关系等。结论:造成上述两物种DNA双链间密码对使用不对称的原因可能是DNA链特异的突变偏好性和在复制、转录、翻译水平上的自然选择约束。Objective：In order to study asymmetry of codon-pair usage between DNA double strands,the patterns of codon-pair usage of the genomes of Rickettsia_bellii and Anaeromyxobacter_dehalogenans_2CP-C were analysed.And these two genomes have extremely biased genomic compositions.Method：Biostatistics.Result：It was found that there were 17 percent and 21 percent of codon pairs of which biases were opposite between genes located on the leading and lagging strands in the genomes of Anaeromyxobacter_dehalogenans_ 2CP-C and Rickettsia_bellii.The results indicated that the differences of codon-pair usage bias existed between the leading and the lagging strand.Therefore,one of important factors that influence codon pairing was the strand-specific features.And these features may included the biased codon usage,gene orientation bias,context-dependent codon bias etc.Conclusion：Asymmetry of codon-pair usage between DNA double strands in above two genomes seemd to be the result of strand-specific mutational biases,and natural selection at the probably acting at the levels of replication,transcription and translation.

关 键 词：密码对使用 不对称性 前导链 滞后链 

分 类 号：Q615[生物学—生物物理学]