Interaction between relaxase MbeA and accessory protein MbeC of the conjugally mobilizable plasmid ColE1

MbeA and MbeC are two key proteins in plasmid ColE1 conjugal mobilization. Isothermal titration calorimetry was used to detect and quantify an interaction between MbeA and MbeC. As a result of this interaction, the affinity of MbeA for single stranded DNA increased. The interaction was confirmed in vivo using a bacterial two-hybrid system, which revealed that MbeA–MbeC complexes are formed through the amino-terminal region of MbeA and the carboxy-terminal region of MbeC. To the best of our knowledge, this is the first report of direct interactions between conjugative proteins encoded by a mobilizable plasmid.Structured summary of protein interactionsmbeA and mbeCphysically interact by two hybrid (View interaction)mbeA and mbeCbind by isothermal titration calorimetry (View interaction)

► ITC was used to detect and quantify interaction between MbeA_ColE1 and MbeC_ColE1.
► The MbeA–MbeC interaction increases the affinity of MbeA for ssDNA.
► The interaction was confirmed in vivo using a 2HB system.
► The complexes are formed through the MbeA N-terminal and the MbeC C-terminal region.
► This is the first report of direct protein-interactions from a mobilizable plasmid.