Pore-forming colicins: synthesis, extracellular release, mode of action, immunity.
Colicins are bacterial toxins encoded by plasmids which also confer immunity to producing cells. In a first stage, colicins are synthesized in the cytoplasm of colicinogenic cells. Subsequently they are released into the extracellular medium following the action of a small protein synthesized coordinately with the colicins. This protein is a lipoprotein and causes a non-specific increase in the envelope permeability, in particular, through the activation of an outer membrane phospholipase. After release into the medium, colicins kill sensitive cells in 3 defined steps: adsorption onto a specific receptor at the surface of the bacterium, translocation across the outer membrane and action. A specific domain of the colicin molecule is responsible for each of these steps. The most common colicins are those which kill by depolarizing the cytoplasmic membrane with the formation of voltage-dependent ionic channels. Immunity is conferred to producing cells by a membrane protein which interacts with the colicin and prevents formation or functioning of these ionic channels formed by its C-terminal domain.
Lazdunski
C J
CJ
Centre de Biochimie et de Biologie Moléculaire du CNRS, Marseille, France.
D001426:Bacterial Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D003087:Colicins / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic / Q000378:metabolism; D014764:Viral Proteins
D001426:Bacterial Proteins; D003087:Colicins; C029555:E protein, bacteriophage X174; D029968:Escherichia coli Proteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; D014764:Viral Proteins; C028593:colicin receptor, E coli