Mutational Analysis of the Locus of Enterocyte Effacement-Encoded Regulator (Ler) of Enteropathogenic Escherichia coli
| Autor: | Gal Yerushalmi, Chen Nadler, Ilan Rosenshine, Tatiana Berdichevski |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Molecular Biology of Pathogens
Genetics Operon Escherichia coli Proteins Mutant food and beverages Virulence Gene Expression Regulation Bacterial Biology medicine.disease_cause Microbiology Pathogenicity island Protein Structure Tertiary Enteropathogenic Escherichia coli Mutation Trans-Activators medicine bacteria Molecular Biology Escherichia coli Gene Locus of enterocyte effacement |
| Zdroj: | Journal of Bacteriology. 190:7808-7818 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.00663-08 |
| Popis: | The locus of enterocyte effacement (LEE) pathogenicity island of enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC, respectively) comprises a cluster of operons encoding a type III secretion system and related proteins, all of which are essential for bacterial colonization of the host intestines. The LEE1 operon encodes Ler, which positively regulates many EPEC and EHEC virulence genes located in the LEE region and elsewhere in the chromosome. In addition, Ler is a specific autorepressor of LEE1 transcription. To better understand the function of Ler, we screened for Ler mutants defective in autorepression. We isolated 18 different point mutations in Ler, rendering it defective in autorepression and in DNA binding. Among these mutants were those defective in positive regulation as well as in autorepression, dominant-negative mutants, and a mutant deficient in oligomerization. Importantly, a group of Ler autorepression mutants complemented an EPEC ler deletion mutant for transcription activation in a dosage-dependent manner, suggesting that Ler and possibly other autorepressors have an intrinsic compensatory mechanism that enables them to sustain mutations. In addition, the phenotypes of the different mutants identified by the screen define a novel domain in Ler that is required for oligomerization. |
| Databáze: | OpenAIRE |
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