Identification of enteropathogenic E. coli (EPEC) virulence genes required for pathogenesis using C. elegans
¹Esther Wong, Shantanu Bhatt, Akwasi Anyanful, and Daniel Kalman
¹Department of Pathology and Laboratory Medicine, Emory University;

Abstract

Enteropathogenic Escherichia coli (EPEC) is a leading cause of persistent diarrhea in developing countries and kills about two million infants annually. To better understand the mechanisms of EPEC virulence, an EPEC::Caenorhabditis elegans model has been developed to determine how toxins secreted by EPEC paralyze then kill the nematode, C. elegans. It has been recently established that EPEC mediated killing requires tryptophan and the tryptophanase gene. To identify novel genes which are essential in EPEC virulence against C. elegans, an EPEC mutant library was generated by electroporation of a transposon into EPEC resulting in random insertions into the genome. 700 EPEC mutant strains were screened and 7 failed to kill C. elegans. Of these mutants, four correspond to the tryptophanase pathway, while three inserted into novel pathways crucial for EPEC pathogenesis. These sites of insertion will provide leads to further identify factors which influence EPEC virulence against C. elegans. Isolation of these mutated genes is the next step in determining important pathways which affect EPEC-induced killing of C. elegans and possibly humans.

In Plain English

My research delt with the interaction between the worm, C. elegans, and a bacteria called enteropathogenic E. coli (EPEC). I tried to find the specific genes which make EPEC lethal to the worm. Normally, EPEC kills C. elegans. So to isolate specific genes which are important in making E. coli harmful, I used a technique called transposon mutagenesis. This is a technique which mutates the EPEC's genome by the insertion of a smaller piece of DNA called a transposon. By mutating EPEC's DNA, we could screen to see which EPEC mutants did not kill C. elegans. If an EPEC mutant did not kill C. elegans, than we would know that the gene which was mutated is crucial in making EPEC harmful. I found 7 EPEC mutants that failed to kill C. elegans and am in the process of isolating the specific genes which have been mutated.

Techniques

electroporation, transposon mutagenesis

Keywords

bacterial genetics, pathology, C. elegans, EPEC, microbial pathogenesis