Goldberg M D, Johnson M, Hinton J C, Williams P H
Department of Microbiology and Immunology, School of Medicine, Maurice Shock Building, PO Box 138, University Road, Leicester LE1 9HN, UK.
Mol Microbiol. 2001 Aug;41(3):549-59. doi: 10.1046/j.1365-2958.2001.02526.x.
Virulence gene expression in enteropathogenic Escherichia coli (EPEC) is governed by a combination of environmental factors and virulence regulators. These factors control the expression of the bundle-forming pili (BFP), intimin, the type III secretion apparatus and the secreted proteins EspA, EspB, EspD and Tir. Expression of the bfp genes occurs for a short period in early exponential phase during growth in tissue culture medium. The nucleoid-associated regulator protein, Fis, is also expressed transiently during this period. To determine whether Fis was responsible for the growth phase-dependent expression of bfp, fis was deleted from the EPEC strain E2348/69S. Paradoxically, the Delta fis mutant retained the ability to colonize HEp-2 cells in a characteristic localized adherence pattern, and Fis was found negatively to regulate the expression of BFP. However, the Delta fis mutant failed to induce the accretion of filamentous actin, which is associated with attaching and effacing lesions. Using a combination of Western blotting and a novel multiplex primer extension assay (MPEA), we showed that, although the expression of intimin and Tir was not affected, transcription of the LEE4 operon encoding espADB and the virulence activator, Ler, were found to be Fis dependent.
肠致病性大肠杆菌（EPEC）中的毒力基因表达受环境因素和毒力调节因子共同调控。这些因素控制着束状菌毛（BFP）、紧密素、Ⅲ型分泌系统以及分泌蛋白EspA、EspB、EspD和Tir的表达。在组织培养基中生长时，bfp基因在指数生长期早期短暂表达。类核相关调节蛋白Fis在此期间也短暂表达。为确定Fis是否负责bfp的生长阶段依赖性表达，从EPEC菌株E2348/69S中删除了fis。矛盾的是，Δfis突变体仍具有以特征性局部黏附模式定殖于HEp-2细胞的能力，且发现Fis负向调节BFP的表达。然而，Δfis突变体未能诱导丝状肌动蛋白的积聚，而丝状肌动蛋白的积聚与紧密黏附损伤有关。通过蛋白质免疫印迹法和一种新型多重引物延伸分析（MPEA）相结合的方法，我们发现，尽管紧密素和Tir的表达未受影响，但编码espADB的LEE4操纵子和毒力激活因子Ler的转录依赖于Fis。
