CsrA and TnaB Coregulate Tryptophanase Activity To Promote Exotoxin-Induced Killing of Caenorhabditis elegans by Enteropathogenic Escherichia coli

Abstract

Enteropathogenic Escherichia coli (EPEC) requires the tnaA-encoded enzyme tryptophanase and its sub- strate tryptophan to synthesize diffusible exotoxins that kill the nematode Caenorhabditis elegans. Here, we demonstrate that the RNA-binding protein CsrA and the tryptophan permease TnaB coregulate tryptophanase activity, through mutually exclusive pathways, to stimulate toxin-mediated paralysis and killing of C. elegans.