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.
Baty
D
D
Centre de Biochimie et de Biologie Moléculaire du CNRS, Marseilles, France.
Pattus
F
F
Parker
M
M
Benedetti
H
H
Frenette
M
M
Bourdineaud
J P
JP
Cavard
D
D
Knibiehler
M
M
Lazdunski
C
C
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