Transcription of the Subtilase Cytotoxin Gene subAB 1 in Shiga Toxin-Producing Escherichia coli Is Dependent on hfq and hns

Shiga toxin-producingEscherichia coli (STEC) strains are responsible for outbreaks of foodborne diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. The pathogenicity of those strains can be attributed to, among other factors, the production of toxins. Recently, the subtilase cytotoxin was detected in locus of enterocyte effacement (LEE)-negative STEC, and it was confirmed that it contributes to the cytotoxicity of those STEC strains. Although the mode of action of SubAB1 is under intensive investigation, the regulation of gene expression is currently not known. The global regulatory proteins H-NS and Hfq have impact on many cellular processes and have been described to regulate virulence factors as well. Here, we investigate the role ofhns andhfq in expression ofsubAB 1 as well asstx 2a andcdt-V in anE. coli laboratory strain as well as in wild-type STEC strain TS18/08.