Mode of action of colicins Ia, E1 and K.

Addition of colicins Ia, E1 or K to sensitive Escherichia coli leads to inhibition of macromolecular synthesis and an uncoupling of electron transport from active transport. Recent results indicate that these colicins affect energy metabolism by interacting directly with the cytoplasmic membrane. This results in a transmembrane flow of ions leading to membrane depolarization. It is proposed that the function of the outer membrane colicin receptor is to mediate access of the colicin molecule to the cytoplasmic membrane.