Systematic Identification and Sequence Analysis of the Genomic Islands of the Enteropathogenic Escherichia coli Strain B171-8 by the Combined Use of Whole-Genome PCR Scanning and Fosmid Mapping
Systematic Identification and Sequence Analysis of the Genomic Islands of the Enteropathogenic Escherichia coli Strain B171-8 by the Combined Use of Whole-Genome PCR Scanning and Fosmid Mapping
复制标题
DOI：
10.1128/jb.00625-08
复制
发表时间：
2008-11-01
影响因子：
3.2
通讯作者：
Hayashi, Tetsuya
中科院分区：
文献类型：
--
作者：
Ogura, Yoshitoshi;Abe, Hiroyuki;Hayashi, Tetsuya
肠致病性大肠杆菌（EPEC）和肠出血性大肠杆菌。大肠杆菌（EHEC）是通过形成附着和消退损伤而定殖于肠道的致炎性病原体，所述附着和消退损伤由经由肠上皮细胞消退（LEE）位点上编码的III型分泌系统（T3 SS）移位的效应物诱导。在肠出血性大肠杆菌O 157中，已经确定了许多毒力因子，包括大约40个T3 SS效应子。它们中的大多数在基因组岛（GEI）上编码，例如原噬菌体和整合元件。然而，对于EPEC，没有系统的搜索GEI和其中携带的毒力相关基因已经完成，并且到目前为止仅确定了有限数量的毒力因子。在本研究中，我们进行了系统的和全基因组的调查，在菌株B171-8，EPEC的原型菌株之一，通过全基因组PCR扫描和fosmid定位相结合的使用，并确定了22个大的GEI，包括9个类噬菌体，3个类P2噬菌体，LEE，和3个额外的整合元件。在这些原噬菌体和整合元件上，我们发现了一组T3 SS蛋白的基因，总共33个T3 SS效应子或效应子同源物，以及12个其他毒力因子，其中包括5个非菌毛粘附素。大多数T3 SS效应子家族也存在于EHEC O 157中，但B171-8的效应子数量明显较少。在分析EPEC和EHEC的致病性时，不仅要考虑滋贺毒素基因的存在与否，而且要考虑T3 SS效应子库的差异。
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are diarrheagenic pathogens that colonize the intestinal tract through the formation of attaching and effacing lesions, induced by effectors translocated via a type III secretion system (T3SS) encoded on the locus of enterocyte effacement (LEE). In EHEC O157, numerous virulence factors, including around 40 T3SS effectors, have been identified. Most of them are encoded on genomic islands (GEIs) such as prophages and integrative elements. For EPEC, however, no systematic search of GEIs and virulence-related genes carried therein has been done, and only a limited number of virulence factors have been identified so far. In this study, we performed a systemic and genome-wide survey of the GEIs in strain B171-8, one of the prototype strains of EPEC, by the combined use of whole-genome PCR scanning and fosmid mapping and identified 22 large GEIs, including nine lambda-like prophages, three P2-like prophages, the LEE, and three additional integrative elements. On these prophages and integrative elements, we found genes for a set of T3SS proteins, a total of 33 T3SS effectors or effector homologues, and 12 other virulence factors which include five nonfimbrial adhesins. Most of the T3SS effector families identified are also present in EHEC O157, but B171-8 possesses a significantly smaller number of effectors. Not only the presence or absence of Shiga toxin genes but also the difference in the T3SS effector repertoire should be considered in analyzing the pathogenicity of EPEC and EHEC strains.