Uptake across the cell envelope and insertion into the inner membrane of ion channel-forming colicins in E coli.
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.
Centre de Biochimie et de Biologie Moléculaire du CNRS, Marseilles, France.
D
D
Baty
F
F
Pattus
M
M
Parker
H
H
Benedetti
M
M
Frenette
J P
JP
Bourdineaud
D
D
Cavard
M
M
Knibiehler
C
C
Lazdunski
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D003087:Colicins / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007473:Ion Channels / Q000378:metabolism*; D008564:Membrane Potentials; D008954:Models, Biological; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000378:metabolism; D011487:Protein Conformation; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic / Q000378:metabolism
D001426:Bacterial Proteins; D003087:Colicins; D029968:Escherichia coli Proteins; D007473:Ion Channels; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C028593:colicin receptor, E coli; D010447:Peptide Hydrolases