Hensel M, Shea J E, Bäumler A J, Gleeson C, Blattner F, Holden D W
Lehrstuhl für Bakteriologie, Max von Pettenkofer-Institut für Hygieneund Medizinische Mikrobiologie, Munich, Germany.
J Bacteriol. 1997 Feb;179(4):1105-11. doi: 10.1128/jb.179.4.1105-1111.1997.
We recently identified a pathogenicity island (SPI2) located at 30.7 centisomes on the Salmonella typhimurium chromosome. SPI2 contains genes encoding a type III secretion system whose function is distinct from that of the type III secretion system encoded by a pathogenicity island (SPI1) at 63 centisomes which is involved in epithelial cell entry. An analysis of the boundaries of SPI2 and comparison with the corresponding region of the Escherichia coli chromosome revealed that SPI2 inserted adjacent to the tRNA(Val) gene. The E. coli chromosome contains 9 kb of DNA at the region corresponding to the SPI2 insertion point which appears to be absent in S. typhimurium. The distribution of SPI1 and SPI2 was examined in various Salmonella isolates. In contrast to type III secretion system genes of SPI1, those of SPI2 are not present in Salmonella bongori, which diverged at the first branch point in the Salmonella lineage. These and other data indicate that SPI2 was acquired by a Salmonella strain already harboring SPI1 by horizontal transfer from an unknown source.
我们最近在鼠伤寒沙门氏菌染色体上30.7厘摩处鉴定出一个致病岛（SPI2）。SPI2包含编码III型分泌系统的基因，其功能与位于63厘摩处参与上皮细胞侵入的致病岛（SPI1）所编码的III型分泌系统不同。对SPI2边界的分析以及与大肠杆菌染色体相应区域的比较表明，SPI2插入到tRNA（Val）基因附近。大肠杆菌染色体在对应于SPI2插入点的区域含有9 kb的DNA，而在鼠伤寒沙门氏菌中似乎不存在该区域。我们检测了各种沙门氏菌分离株中SPI1和SPI2的分布。与SPI1的III型分泌系统基因不同，SPI2的基因不存在于邦戈沙门氏菌中，邦戈沙门氏菌在沙门氏菌谱系的第一个分支点处发生了分化。这些以及其他数据表明，SPI2是由一个已经携带SPI1的沙门氏菌菌株通过从未知来源水平转移而获得的。
