[ODP-155] The expression of MacAB is controlled by Rof through Rho dependent transcription termination system
The ATP-binding cassette-type drug efflux pump MacAB was originally reported as a macrolide specific pump. It is also known to be required for the virulence of Salmonella enterica when mice are inoculated via the oral route. MacAB exports not only antibiotics but also some kind of natural substrates such as linearized siderophore products. Linearized siderophore products protect S. enterica from oxidative stress and this is required for this organism to survive in macrophages. The expression level of the macAB genes in S.enterica are low in a normal medium and those repression mechanism is not well understood. In this study, we attempted to identify the factor that affect the macAB expression. Firstly, genomic DNA was extracted from S.enterica, then digested with the restriction enzyme and inserted into the vector to make a genomic plasmid library. Then, the chromosomal macAB-lacZY fusion strain was transformed with the library for the screening of plasmids that affect the promoter activity of the macAB operon. Five candidate plasmids were isolated and three of them contained the yaeR-rof operon. It is suggested that Rof controls the expression of MacAB through Rho dependent transcription termination which locates at untraslated region upstream of macAB. This insight could lead to better understandings of the regulatory mechanism macAB in S. enterica.