The H-NS protein represses transcription of the eltAB operon, which encodes heat-labile enterotoxin in enterotoxigenic Escherichia coli, by binding to regions downstream of the promoter

Abstract

Heat-labile enterotoxin, a major virulence determinant of enterotoxigenic Escherichia coli, is encoded by the eltAB operon. To elucidate the molecular mechanism by which the heat-stable nucleoid-structural (H-NS) protein controls transcription of eltAB, the authors constructed an eltAB-lacZ transcriptional fusion and performed β-galactosidase analysis. The results showed that H-NS protein exerts fivefold repression on transcription from the eltAB promoter at 37 °C and 10-fold repression at 22 °C. Two silencer regions that were required for H-NS-mediated repression of eltAB expression were identified, both of which were located downstream of the start site of transcription. One silencer was l..