Comparison of two major forms of the Shigella virulence plasmid pINV:: Positive selection is a major force driving the divergence
Comparison of two major forms of the Shigella virulence plasmid pINV:: Positive selection is a major force driving the divergence
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DOI：
10.1128/iai.71.11.6298-6306.2003
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发表时间：
2003-11-01
影响因子：
3.1
通讯作者：
Reeves, PR
中科院分区：
文献类型：
--
作者：
Lan, RT;Stevenson, G;Reeves, PR
所有志贺氏菌和肠侵袭性大肠杆菌（EIEC）菌株都携带一个230 kb的毒力质粒（pINV），这是其侵袭性所必需的。质粒有两种序列形式，pINV A和pINV B（R.兰，B。Lumb，D.瑞恩和公关部里夫斯感染Immun. 69：6303-6309，2001），并且最近测序的来自福氏志贺菌血清型5的pINV质粒是pINV B形式。在本研究中，我们对来自福氏志贺菌血清型6的pINV A型的大部分编码区（插入序列或相关序列除外）进行了测序，并将其与pINV B型进行了比较。超过一半的基因测序似乎是根据积极的选择，其同义与非同义取代的比例低。这种高比例的选择性差异表明两种pINV形式具有功能差异，并且在不同志贺氏菌-EIEC菌株中的致病性的比较研究可以提供信息。在S.目的：构建含丝氨酸蛋白酶基因的弗氏6型质粒，该基因编码的丝氨酸蛋白酶是弗氏6型志贺菌的主要分泌蛋白。flexneri血清型2a和stbAB基因，其编码在S.福氏血清型5。两种pINV形式的不相容性似乎是由于mvpAT分离后杀伤系统的微小差异或pINVA中存在未知系统所致。
All Shigella and enteroinvasive Escherichia coli (EIEC) strains carry a 230-kb virulence plasmid (pINV) which is essential for their invasiveness. There are two sequence forms, pINV A and pINV B, of the plasmid (R. Lan, B. Lumb, D. Ryan, and P. R. Reeves, Infect. Immun. 69:6303-6309, 2001), and the recently sequenced pINV plasmid from Shigella flexneri serotype 5 is a pINV B form. In this study we sequenced the majority of the coding region of the pINV A form from S.flexneri serotype 6 other than insertion sequence or related sequences and compared it with the pINV B form. More than half of the genes sequenced appear to be under positive selection based on their low ratio of synonymous to nonsynonymous substitutions. This high proportion of selected differences indicates that the two pINV forms have functional differences, and comparative studies of pathogenicity in different Shigella-EIEC strains could be informative. There are also genes absent in the S. flexneri serotype 6 plasmid, including the sepA gene encoding serine protease, the major secreted protein of S. flexneri serotype 2a, and the stbAB genes, which encode one of the two partition systems found in S. flexneri serotype 5. The incompatibility of the two pINV forms appears to be due to either small differences in the mvpAT postsegregational killing system or the presence of an unknown system in pINVA.