摘要
由于伪狂犬病病毒(PRV)中G+C含量高达74%,至今尚没有一个毒株完成全基因组测序。对已知的68 个PRV基因编码区序列碱基组成及密码子使用现象进行了统计分析,结果发现PRV基因中存在非常强的密码子使用偏差。所有68个PRV基因编码区密码子第三位总的G+C含量为96.24%,其中UL48基因高达99.52%。PRV基因偏向于使用富含GC的密码子,特别是以C或G结尾的密码子。此外,还发现PRV中G+C含量变化较大的UL48、UL40、UL14和IE180等基因附近正好与已知的PRV基因组复制起始区相对应。根据基因功能将PRV基因分为6类进行分析发现,基因功能相同或相近的基因其密码子使用模式相似,其中调节基因的同义密码子相对使用度(RSCU)与其他基因有显著差异,在调节基因中以C结尾的密码子的RSCU值远大于其他同义密码子。最后,对PRV基因氨基酸组成差异进行多元分析,发现不同功能的PRV基因在对应分析图上分布不同,表明PRV基因密码子使用模式可能与基因功能相关。
The complete sequence of the Pseudorabies Virus (PRV) genomic DNA has not yet been determined,primarily because of the high content of G+C nucleotides of about 74%.We examined the base composition and codon usage of the 68 known PRV genes.As a result,we found a strong bias towards GC rich codons especially NNC or NNG (N represents any one of four nucleotides) in PRV genes.This demonstrated that the usage bias of synonymous codon and amino acid is the main cause of the high G+C content of PRV .The results showed that the genome regions adjacent UL48,UL40,UL14,IE180 genes where the G+C content occurs as pronounced waves are corresponding to the replication origins.It was also found that the codon usage patterns of regulatory genes are apparently different from other PRV genes.A corresponding analysis of amino acid compositions indicated that the bias of codon usage could be relatied to the differences of gene function.
基金
国家自然科学基金项目(编号:39970559,30400322)~~
