THE INCP PLASMID-ENCODED CELL ENVELOPE-ASSOCIATED DNA TRANSFER COMPLEX INCREASES CELL-PERMEABILITY

IncP-type plasmids are broad-host-range conjugative plasmids. DNA tran slocation requires DNA transfer-replication functions and additional f actors required for mating pair formation (Mpf). The Mpf system is loc ated in the cell membranes and is responsible for DNA transport from t he donor to the recipient. The Mpf complex acts as a receptor for IncP -specific phages such as PRD1. In this investigation, we quantify the Mpf complexes on the cell surface by a phage receptor saturation techn ique. Electrochemical measurements are used to show that the Mpf compl ex increases cell envelope permeability to lipophilic compounds and AT P. In addition it reduces the ability of the cells to accumulate K+. H owever, the Mpf complex does not dissipate the membrane voltage. The M pf complex is rapidly disassembled when intracellular ATP concentratio n is decreased, as measured by a PRD1 adsorption assay.