Colicin E1 binding to membranes: time-resolved studies of spin-labeled mutants.
To investigate the mechanism of interaction of the toxin colicin E1 with membranes, three cysteine substitution mutants and the wild type of the channel-forming fragment were spin labeled at the unique thiol. Time-resolved interaction of these labeled proteins with phospholipid vesicles was investigated with stopped-flow electron paramagnetic resonance spectroscopy. The fragment interacts with neutral bilayers at low pH, indicating that the interaction is hydrophobic rather than electrostatic. The interaction occurs in at least two distinct steps: (i) rapid adsorption to the surface; and (ii) slow, rate-limiting insertion of the hydrophobic central helices into the membrane interior.
Jules Stein Eye Institute, University of California, Los Angeles 90024.
Y K
YK
Shin
C
C
Levinthal
F
F
Levinthal
W L
WL
Hubbell
D000327:Adsorption; D001665:Binding Sites; D002462:Cell Membrane / Q000378:metabolism*; D003087:Colicins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000235:genetics; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism; D016296:Mutagenesis; D010446:Peptide Fragments / Q000378:metabolism; D017433:Protein Structure, Secondary; D013113:Spin Labels
D003087:Colicins; D008051:Lipid Bilayers; D010446:Peptide Fragments; D013113:Spin Labels; D003545:Cysteine