Comparative genomics reveal the mechanism of the parallel evolution of O157 and non-O157 enterohemorrhagic Escherichia coli
Comparative genomics reveal the mechanism of the parallel evolution of O157 and non-O157 enterohemorrhagic Escherichia coli
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DOI：
10.1073/pnas.0903585106
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发表时间：
2009-10-20
影响因子：
11.1
通讯作者：
Hayashi, Tetsuya
中科院分区：
文献类型：
--
作者：
Ogura, Yoshitoshi;Ooka, Tadasuke;Hayashi, Tetsuya
在各种致病性大肠杆菌菌株中，肠出血性大肠杆菌（EHEC）最具破坏性。尽管 O157:H7 血清型菌株最为流行，但不同血清型的菌株也具有相似的致病潜力。在这里，我们展示了血清型 O157、O26、O111 和 O103 的 EHEC 以及其他 21 种完全测序的大肠杆菌/志贺氏菌菌株之间的基因组比较结果。所有肠出血性大肠杆菌都比其他菌株具有更大的基因组 (5.5-5.9 Mb)，并且含有数量惊人的原噬菌体和整合元件 (IE)。 4种肠出血性大肠杆菌的基因内容并不遵循菌株的系统发育关系，它们共享志贺毒素和许多其他因子的毒力基因。我们发现许多羔羊噬菌体、IE和毒力质粒携带相同或相似的毒力基因，但具有不同的进化历史，表明这些移动遗传元件的独立获取驱动了每个肠出血性大肠杆菌的进化。特别有趣的是 III 型分泌系统（T3SS）的进化。我们发现肠出血性大肠杆菌的T3SS由3种不同类型的遗传元件引入的基因组成：IE，称为肠细胞消失位点，它编码T3SS的中心部分；类似 SpLE3 的 IE；以及携带大量 T3SS 效应基因和其他 T3SS 相关基因的羔羊噬菌体。我们的数据证明了不同系统发育的大肠杆菌菌株如何独立进化为肠出血性大肠杆菌，为细菌中复杂毒力系统平行进化的机制提供了独特的见解。
Among the various pathogenic Escherichia coli strains, enterohemorrhagic E. coli (EHEC) is the most devastating. Although serotype O157:H7 strains are the most prevalent, strains of different serotypes also possess similar pathogenic potential. Here, we present the results of a genomic comparison between EHECs of serotype O157, O26, O111, and O103, as well as 21 other, fully sequenced E. coli/Shigella strains. All EHECs have much larger genomes (5.5-5.9 Mb) than the other strains and contain surprisingly large numbers of prophages and integrative elements (IEs). The gene contents of the 4 EHECs do not follow the phylogenetic relationships of the strains, and they share virulence genes for Shiga toxins and many other factors. We found many lambdoid phages, IEs, and virulence plasmids that carry the same or similar virulence genes but have distinct evolutionary histories, indicating that independent acquisition of these mobile genetic elements has driven the evolution of each EHEC. Particularly interesting is the evolution of the type III secretion system (T3SS). We found that the T3SS of EHECs is composed of genes that were introduced by 3 different types of genetic elements: an IE referred to as the locus of enterocyte effacement, which encodes a central part of the T3SS; SpLE3-like IEs; and lambdoid phages carrying numerous T3SS effector genes and other T3SS-related genes. Our data demonstrate how E. coli strains of different phylogenies can independently evolve into EHECs, providing unique insights into the mechanisms underlying the parallel evolution of complex virulence systems in bacteria.