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Study on molecular basis of bacteria-host cell interaction in enteropathogenic Escherichia coli adherence.

致病性大肠杆菌粘附中细菌-宿主细胞相互作用的分子基础研究。

基本信息

批准号：
14570236
负责人：
TOBE Toru
金额：
$ 2.56万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

Enteropathogenic Escherichia coli is a causative agent of diarrhea in human. Adherence to intestinal epithelial cells is crucial for EPEC pathogenicity. Expression of adherence factors and type III secretion activity have shown to be altered during #4 adhesion to epithelial cells. By using DNA microarray, we determined transcript levels of plasmid-or chromosome-oriented virulence-associated genes as well as other EAF plasmid-coding genes in EPEC during adherent to Caco-2 cells. Transcriptions of genes in bfp operon, LEE4 (esp) operon and LEE5 (tir-eae) Operon were enhanced within 1 h after infection, although transcriptions of genes encoding type Ill machinery were not enhanced. Tran8script levels of bfp genes decreased at 2 h post-infection, while transcript levels of LEE4 and LEE5 operon stayed at high for 4-5 h and then decreased at later stage of adherence (5-6 h post infection). On the other hand, transcription of genes presumed to be involved in replication of EAF plasmid increased remarkably at later stage. The copy number of EAF plasmid against chromosome increased at later stage. Enhancement of bfp, LEE4 or LEE5 transcription was not abolished by escC mutation or eae mutation, while, reduction of LEE4 and LEE5 transcription at later stage and increase of EAF plasmid copy number was diminished by these mutations. The results suggested that transcription of bfp~, LEE4 and LEE5 operons were enhanced or repressed differentially during adherence by responding to changes in interaction with host cells.

肠致病性大肠杆菌是引起人类腹泻的病原体。粘附于肠上皮细胞是EPEC致病性的关键。粘附因子的表达和III型分泌活性已显示在#4粘附至上皮细胞期间改变。利用DNA微阵列技术，我们检测了EPEC中质粒或染色体定向的毒力相关基因以及其他EAF质粒编码基因在粘附于Caco-2细胞过程中的转录水平。bfp操纵子、LEE 4（esp）操纵子和LEE 5（tir-eae）操纵子中的基因转录在感染后1h内增强，但编码III型机器的基因转录没有增强。bfp基因的转录水平在感染后2 h下降，而LEE 4和LEE 5操纵子的转录水平在4-5 h保持高水平，然后在粘附后期（感染后5-6 h）下降。另一方面，推测参与EAF质粒复制的基因的转录在后期显著增加。EAF质粒对染色体的拷贝数在后期增加。esc C突变和eae突变不能消除bfp、LEE 4和LEE 5转录的增强，但能减少LEE 4和LEE 5转录后期的降低和EAF质粒拷贝数的增加。结果表明，bfp~+、LEE_4和LEE_5操纵子的转录在粘附过程中通过响应与宿主细胞相互作用的变化而被不同地增强或抑制。