Structure and dynamics of the colicin E1 channel.
The toxin-like and bactericidal colicin E1 molecule is of interest for problems of toxin action, polypeptide translocation across membranes, voltage-gated channels, and receptor function. Colicin E1 binds to a receptor in the outer membrane and is translocated across the cell envelope to the inner membrane. Import of the colicin channel-forming domain into the inner membrane involves a translocation-competent intermediate state and a membrane potential-dependent movement of one third to one half of the channel peptide into the membrane bilayer. The voltage-gated channel has a conductance sufficiently large to depolarize the Escherichia coli cytoplasmic membrane. Amino acid residues that affect the channel ion selectivity have been identified by site-directed mutagenesis. The colicin E1 channel is one of a few membrane proteins whose secondary structures in the membrane, predominantly alpha-helix, have been determined by physico-chemical techniques. Hypothesis for the identity of the trans-membrane helices, and the mechanism of binding to the membrane, are influenced by the solved crystal structure of the soluble colicin A channel peptide. The protective action of immunity protein is a unique aspect of the colicin problem, and information has been obtained, by genetic techniques, about the probable membrane topography of the imm gene product.
Cramer
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Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
Cohen
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Merrill
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Song
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D001693:Biological Transport, Active; D003087:Colicins; D029968:Escherichia coli Proteins; D007473:Ion Channels / Q000378:metabolism*; D008969:Molecular Sequence Data; D011487:Protein Conformation; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D003087:Colicins; D029968:Escherichia coli Proteins; C488857:Imm protein, E coli; D007473:Ion Channels; C007104:colicin immunity proteins