Hierarchy in the expression of the locus of enterocyte effacement genes of enteropathogenic Escherichia coli
Hierarchy in the expression of the locus of enterocyte effacement genes of enteropathogenic Escherichia coli
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DOI：
10.1046/j.1365-2958.1999.01655.x
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发表时间：
1999-12-01
影响因子：
3.6
通讯作者：
Rosenshine, I
中科院分区：
文献类型：
--
作者：
Friedberg, D;Umanski, T;Rosenshine, I
肠致病性大肠杆菌 (EPEC) 会引起宿主细胞形态的变化并导致肌动蛋白重排，这种表型通常被称为附着/消失 (AE) 病变。 EPEC 诱导 AE 损伤的能力取决于 III 型蛋白分泌/易位系统，该系统由聚集在 35.6 kb DNA 片段中的基因编码，称为肠细胞消失位点 (LEE)。我们利用绿色荧光蛋白（gfp）报告基因与LEE基因rorf2、orf3、orf5、escJ、escV和eae之间的转录融合，结合Tir、intimin、EspB和EspF抗体的免疫印迹分析，来分析LEE的遗传调控。所有这些 LEE 基因的表达严格依赖于功能性整合宿主因子 (IHF) 的存在。 IHF 特异性结合 ler (orf1) 启动子上游，并似乎直接激活 ler、orf3、orf5 和 rorf2 的表达。 ler 编码的 Ler 蛋白参与激活 escJ、escV、tir、eae、espB 和 espF 的表达。需要 IHF 和 Ler 的表达来引发与 AE 病变相关的肌动蛋白重排。总之，IHF 直接激活 ler 和 rorf2 转录单位的表达，而 Ler 反过来介导其他 LEE 基因的表达。
Enteropathogenic Escherichia coli (EPEC) elicit changes in host cell morphology and cause actin rearrangement, a phenotype that has commonly been referred to as attaching/effacing (AE) lesions. The ability of EPEC to induce AE lesions is dependent upon a type III protein secretion/translocation system that is encoded by genes clustered in a 35.6 kb DNA segment, named the locus of enterocyte effacement (LEE). We used transcriptional fusions between the green fluorescent protein (gfp) reporter gene and LEE genes rorf2, orf3, orf5, escJ, escV and eae, together with immunoblot analysis with antibodies against Tir, intimin, EspB and EspF, to analyse the genetic regulation of the LEE. The expression of all these LEE genes was strictly dependent upon the presence of a functional integration host factor (IHF). IHF binds specifically upstream from the ler (orf1) promoter and appears to activate expression of ler, orf3, orf5 and rorf2 directly. The ler-encoded Ler protein was involved in activating the expression of escJ, escV, tir, eae, espB and espF. Expression of both IHF and Ler was needed to elicit actin rearrangement associated with AE lesions. In conclusion, IHF directly activates the expression of the ler and rorf2 transcriptional units, and Ler in turn mediates the expression of the other LEE genes.