Colicins 1972

Abstract

Colicins are bactericidal proteins synthesized by certain strains of enteric bacteria and active against other strains of the same, or related, bacterial species. The well-studied colicins fall into three groups (Table 1) as defined by their predominant physiological effects: 1. inhibition of protein synthesis; 2. degradation of DNA; and 3. general blockage of energy dependent cellular functions. Colicins of all three classes exert their effects via poorly understood processes involving the cell membrane. Colicins are not antibiotics in the usual sense of the word, since they apparently require specific membrane proteins by means of which they adsorb to, and initiate their attack upon sensitive cells. No effects of colicins upon the cells of unrelated species (including mammalian cells) have been reported, nor have they been reported to attack artifical lipid bilayer membranes. Inclusion of a review of colicins in a volume such as this thus depends on the light their study can shed upon the action of agents of broader spectrum and upon basic mechanisms of attack upon the particular cellular functions affected.