伴放线放线杆菌细胞致死性扩张毒素序列进化分析

摘要

目的:应用生物信息学的方法研究伴放线放线杆菌(4a)细胞致死性扩张毒素(CDT)的3个蛋白亚基在不同细菌中的序列变化情况,为牙周病中Aa菌株的检测提供思路.方法:运用ncbigenbank数据库、蛋白同源性比对(blastP和tblastn)及极大似然法构建进化树等,研究Aa中CDT蛋白的3个亚基在不同菌种的序列保守性.结果:在Genbank数据库674个属的细菌中,发现有20个属27个种含有CDT蛋白亚基,其中11个种的细菌只含有CdtB蛋白亚基.在进化过程中,CdtB与CDT其他两种亚基蛋白相比,序列间的变化无明显相关性,且蛋白序列更为保守.系统进化树分析表明,Aa的CdtB蛋白与嗜血杆菌属、沙门氏菌属和螺杆菌属的细菌有较近的亲缘关系.结论:Aa CDT蛋白复合体的CdtB与其他两个亚基的蛋白在序列进化上存在显著差异,推测一些菌种中CDT蛋白毒性功能的发挥并不需要3个亚基共同存在.%AIM:To predict sequence variation of cytolethal distending toxin(CDT) subunits of A.actinomycetemcomitans (Aa)in different bacteria using bioinformatics methods.METHODS:The ncbi genbank database,blastP,tblastn and maximum likelihood for phylogenetic tree construction in MEGA were used to study sequence variation of 3 CDT subunits in bacteria.RESULTS:27 species in 20 genus containing CDT subunits in 674 bacterial genus were found in genbank database,and 11 species only had CdtB in their genome.CdtB showed more protein sequence conservation than other 2 subunits in CDT,and sequence variation in CdtB is not correlated with other two CDT subunits in bacteria in evolution.Phylogenetic analysis showed that the CdtB sequence in Aa was more closer to species in Helicobacter,Salmonella and Helicobacter genus than other bacteria.CONCLUSION:Sequence evolution in CdtB protein is significantly different with that in other 2 subunits in CDT complex in Aa.A lot of bacteria species only have CdtB in their genome,and the function of CDT in these bacteria may be acted by CdtB alone without other 2 subunits.