Uptake across the cell envelope and insertion into the inner membrane of ion channel-forming colicins in E coli

• Published in: Biochimie Vol. 72; no. 2; pp. 123 - 130
• Main Authors: Baty, D., Pattus, F., Parker, M., Benedetti, H., Frenette, M., Bourdineaud, J.P., Cavard, D., Knibiehler, M., Lazdunski, C.
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.02.1990; Elsevier
• Subjects: Amino Acid Sequence; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Biological Transport; Cell Membrane - metabolism; colicin A; Colicins - metabolism; Escherichia coli - metabolism; Escherichia coli Proteins; Fundamental and applied biological sciences. Psychology; inner membranes; Ion Channels - metabolism; Life Sciences; Membrane Potentials; Microbiology; Models, Biological; Molecular Sequence Data; Peptide Hydrolases - metabolism; Permeability, membrane transport, intracellular transport; Protein Conformation; protein translocation; protein-domains; Receptors, Cell Surface; Receptors, Immunologic - metabolism; voltage-gated channels; voltage-gated channels; protein-domains; protein translocation; Colicin; Cell envelope; Escherichia coli; Plasma membrane; Molecular model; Bacteria; Ionic channel; Review; Escherichieae; Membrane translocation; Enterobacteriaceae; Functional capacity
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/0300-9084(90)90137-6

Pore-forming colicins exert their lethal effect on E coli through formation of a voltage-dependent channel in the inner (cytoplasmic-membrane) thus destroying the energy potential of sensitive cells. Their mode of action appears to involve 3 steps: i) binding to a specific receptor located in the outer membrane; ii) translocation across this membrane; iii) insertion into the inner membrane. Colicin A has been used as a prototype of pore-forming colicins. In this review, the 3 functional domains of colicin A respectively involved in receptor binding, translocation and pore formation, are defined. The components of sensitive cells implicated in colicin uptake and their interactions with the various colicin A domains are described. The 3-dimensional structure of the pore-forming domain of colicin A has been determined recently. This structure suggests a model of insertion into the cytoplasmic membrane which is supported by model membrane studies. The role of the membrane potential in channel functioning is also discussed.