A synthetic peptide corresponding to the C-terminal 25 residues of phage MS2 coded lysis protein dissipates the protonmotive force in Escherichia coli membrane vesicles by generating hydrophilic pores.

The RNA phage MS2 encodes a protein, 75 amino acids long, that is necessary and sufficient for lysis of the host cell. DNA deletion analysis has shown that the lytic activity is confined to the C-terminal half of the protein. We have examined the effects of a synthetic peptide, covering the C-terminal 25 amino acids of the lysis protein, on the electrochemical potential, generated in Escherichia coli membrane vesicles and in liposomes reconstituted with cytochrome c oxidase. In all cases the peptide dissipates the electrochemical potential. The peptide also induces the release of carboxyfluorescein (376 daltons), but not of inuline (5500 daltons), from protein-free liposomes. The phenomena are observed at a lipid to peptide molar ratio of approximately 100:1. The possible connection between the dissipation of the proton-motive force and bacteriolysis is discussed.