Expression regulation of polycistronic lee3 genes of enterohaemorrhagic Escherichia coli

Wei Sheng W. Sun, Jenn Wei Chen, Yi Chih Wu, Hsing Yuan Tsai, Yu Liang Kuo, Wan Jr Syu

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6 Citations (Scopus)


Enterohaemorrhagic Escherichia coli O157:H7 (EHEC) carries a pathogenic island LEE that is consisted mainly of five polycistronic operons. In the lee3 operon, mpc is the first gene and has been reported to down regulate the type-3 secretion system of EHEC when its gene product is over-expressed. Furthermore, mpc has been suggested to have a regulationfunction via translation but the mechanism remains unclear. To clarify this hypothesis, we dissected the polycistron and examined the translated products. We conclude that translationof mpc detrimentally governs the translation of the second gene, escV, which in turn affects the translation of the third gene, escN. Then sequentially, escN affects the expressionof the downstream genes. Furthermore, we located a critical cis element within the mpc open-reading frame that plays a negative role in the translation-dependent regulationof lee3. Using qRT-PCR, we found that the amount of mpc RNA transcript present in EHEC was relatively limited when compared to any other genes within lee3. Taken together, when the transcription of LEE is activated, expression of mpc is tightly controlled by a restriction of the RNA transcript of mpc, translation of which is then critical for the efficient production of the operon's downstream gene products.

Original languageEnglish
Article numbere0155578
JournalPloS one
Issue number5
Publication statusPublished - 2016 May

All Science Journal Classification (ASJC) codes

  • General Biochemistry,Genetics and Molecular Biology
  • General Agricultural and Biological Sciences
  • General


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