Cooperative Function of TraJ and ArcA in Regulating the F Plasmid tra Operon

Abstract

Conjugation is a major mechanism for dissemination of antibiotic resistance and virulence among bacterial populations. The tra operon in the F family of conjugative plasmids encodes most of the proteins involved in bacterial conjugation. This work reveals that activation of tra operon transcription requires two proteins, TraJ and ArcA, to bind cooperatively to adjacent sites immediately upstream of the major tra promoter P Y . The interaction of TraJ and ArcA with the tra operon not only relieves P Y from silencers but also directly activates it. These findings provide insights into the regulatory circuit of the F-family plasmid-mediated bacterial conjugation.