Distribution, functional expression, and genetic organization of Cif, a phage-encoded type III-secreted effector from enteropathogenic and enterohemorrhagic Escherichia coli
Distribution, functional expression, and genetic organization of Cif, a phage-encoded type III-secreted effector from enteropathogenic and enterohemorrhagic Escherichia coli
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DOI：
10.1128/jb.00844-07
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发表时间：
2008-01-01
影响因子：
3.2
通讯作者：
Oswald, Eric
中科院分区：
文献类型：
--
作者：
Loukiadis, Estelle;Nobe, Rika;Oswald, Eric
肠致病性大肠杆菌（EPEC）和肠出血性大肠杆菌。大肠杆菌（EHEC）通过肠上皮细胞消失位点（LEE）编码的III型分泌系统将效应蛋白注入宿主细胞。其中一个效应子是Cif，它在LEE外由一个拟杆菌前噬菌体编码。在这项研究中，我们证明了Cif编码的EPEC菌株E22的前噬菌体是可诱导的，并产生感染性的噬菌体颗粒。我们研究了Cif在5，049株大肠杆菌中的分布和功能表达。人、动物和环境来源的大肠杆菌菌株。共115个E。来自不同来源和地理位置的大肠杆菌分离株携带CIF。CIF的存在与LEE密切相关，因为所有CIF阳性分离株均为LEE阳性。这些结果表明，编码Cif的原噬菌体已广泛分布在E.大肠杆菌，但积极选择的人口LEE阳性菌株。尽管如此，66%的cif阳性E.由于cif基因的移码突变或IS元件的插入，大肠杆菌菌株没有在真核细胞中诱导典型的Cif相关表型。携带cif的原噬菌体的乘客区是高度可变的，并且显示IS元件和编码其他效应物的基因的各种组合，如nleB、nleC、nleH、nleG、espj和nleA/espI（其中一些也被截短）。在评估EPEC和EHEC的致病性和嗜性时，应考虑到这种多样性和非功能性效应物的存在。
Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) inject effector proteins into host cells via a type III secretion system encoded by the locus of enterocyte effacement (LEE). One of these effectors is Cif, encoded outside the LEE by a lambdoid prophage. In this study, we demonstrated that the Cif-encoding prophage of EPEC strain E22 is inducible and produces infectious phage particles. We investigated the distribution and functional expression of Cif in 5,049 E. coli strains of human, animal, and environmental origins. A total of 115 E. coli isolates from diverse origins and geographic locations carried cif. The presence of cif was tightly associated with the LEE, since all the cif-positive isolates were positive for the LEE. These results suggested that the Cif-encoding prophages have been widely disseminated within the natural population of E. coli but positively selected within the population of LEE-positive strains. Nonetheless, 66% of cif-positive E. coli strains did not induce a typical Cif-related phenotype in eukaryotic cells due to frameshift mutations or insertion of an IS element in the cif gene. The passenger region of the prophages carrying cif was highly variable and showed various combinations of IS elements and genes coding for other effectors such as nleB, nleC, nleH, nleG, espj, and nleA/espI (some of which were also truncated). This diversity and the presence of nonfunctional effectors should be taken into account to assess EPEC and EHEC pathogenicity and tropism.