Sekizaki T, Osaki M, Takamatsu D, Shimoji Y
National Institute of Animal Health, Tsukuba, Ibaraki, Japan.
J Bacteriol. 2001 Sep;183(18):5436-40. doi: 10.1128/JB.183.18.5436-5440.2001.
The SsuDAT1I restriction-modification (R-M) system, which contains two methyltransferases and two restriction endonucleases with recognition sequence 5'-GATC-3', was first found in a field isolate of Streptococcus suis serotype 2. Isoschizomers of the R-M system were found in the same locus between purH and purD in a field isolate of serotype 1/2 and the reference strains of serotypes 3, 7, 23, and 26 among 29 strains of different serotypes examined in this study. The R-M gene sequences in serotypes 1/2, 3, 7, and 23 were very similar to those of SsuDAT1I, whereas those in serotype 26 were less similar. These results indicate intraspecies recombination among them and genetic divergence through their evolution.
SsuDAT1I 限制修饰(R-M)系统包含两种甲基转移酶和两种识别序列为 5'-GATC-3' 的限制性内切酶,该系统最初在猪链球菌 2 型的一株田间分离株中发现。在本研究检测的 29 株不同血清型菌株中,在血清型 1/2 的一株田间分离株以及血清型 3、7、23 和 26 的参考菌株中,于 purH 和 purD 之间的同一基因座发现了该 R-M 系统的同裂酶。血清型 1/2、3、7 和 23 中的 R-M 基因序列与 SsuDAT1I 的序列非常相似,而血清型 26 中的序列相似性较低。这些结果表明它们之间存在种内重组以及在进化过程中的遗传分化。