In Vivo Expression of the β-Glucoside ( bgl ) Operon of Escherichia coli Occurs in Mouse Liver

Abstract

ABSTRACT An Escherichia coli DNA fragment was identified that contained part of the β-glucoside ( bgl ) operon. This fragment was identified because it contained a promoter that was responsible for the expression of a reporter gene, the chloramphenicol acetyltransferase gene, in a mouse liver during bacterial infection but not when a bacterial clone was grown in vitro. This fragment contained a promoter and a rho-independent transcription terminator which were flanked by the 3′ end of bglG and the 5′ end of bglF . Reverse transcription-PCR confirmed that cat -specific mRNA was produced in infected mouse liver but not in vitro. mRNA encoding the positive regulator of the bgl operon, bglG , also was detected in mouse liver infected with an E. coli strain. These results demonstrated that expression of the bgl operon occurs in infected mouse liver and suggests a unique role for this operon in vivo.