从密码子和16S核糖体分析鼠疫菌的进化

摘要

Objective To explore the mutation and evolution of Yersiniapestis(Y. pestis) from the point of codon and 16S-ribosome. Methods Codon preference and 16S-ribosome of Y. pestis were analyzed by bioinformatics. Results Similar codon preference was found among 4 PCD1 Y. pestis, of the 3 old Y. pestis the codon preference between PMT1 and PCD1 was similar. There were some differences between PCD1, PCP1 and Yunnan 6 kb plasmid. Through the analysis of 16S-ribosome, the sequences were found similar in 11 strains of Y. pestis,Yersinia pseudotuberculosis was very close to Y. pestis, with only one nucleotide difference, mutated G-T, and corresponding amino acid methionine (M)-isoleucine (I). There were some differences in sequences of 16S-ribosome in Y. pestis, Escherichia coli and Pulex irritans. Conclusions The time for Y. pestis to obtain PCP1 is later than PMT1 does, in other words, the affinity of Y. pestis with PMT1 was closer than PCP1 with 6 kb plasmid;alteration of 16S-ribosomal nucleotide sites may cause changes in function and structure of 16S rRNA. The lower similarity between 16S-ribosomal sequences of Y. pestis and Pulex irritans indicates the time for co-evolution is very short,and the late emergence of Y. pestis.%目的 从密码子和16S核糖体的角度探讨鼠疫菌的突变和进化.方法 利用生物信息学工具对鼠疫菌的密码子偏好和16S核糖体进行分析.结果 密码子分析发现4株耶尔森菌的低钙反应质粒(PCD1)密码子偏好相似,古老型鼠疫菌的3个质粒中鼠毒素质粒(PMT1)和PCD1质粒密码子相似,而PCD1、鼠疫菌素质粒(PCP1)和云南鼠疫菌PYC(6 kb)质粒的密码子偏好有一定的差异.16S核糖体分析发现11株耶尔森菌的16S核糖体序列相似,其中假结核和鼠疫菌最接近,只有1个碱基的差别,经过分析发现鼠疫菌的这个位点的碱基发生了突变,由G变成T,相应的氨基酸也由甲硫氨酸(M)变成异亮氨酸(I);而鼠疫菌的16S核糖体序列与大肠埃希菌、人蚤有一定的区别.结论 鼠疫菌获得PCP1的时间可能要比PMT1晚,或者说鼠疫菌与PMT1的亲缘性要比PCP1和云南6 kb质粒相近;鼠疫菌16S核糖体核苷酸位点的改变可能会导致16S rRNA功能和结构的改变,而鼠疫菌16S核糖体的序列与人蚤相似性很低,推断其协同进化时间很短,说明鼠疫菌的出现很晚.