Open Accesshaemolysin of Escherichia coli : Comparison of pore‐forming properties between chromosome and plasmid‐encoded haemolysins
Author(s) -
Benz Roland,
Döbereiner Andreas,
Ludwig Albrecht,
Goebel Werner
Publication year - 1992
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1992.tb05887.x
Subject(s) - hemolysin , lipid bilayer , conductance , bilayer , biophysics , chemistry , membrane , ion channel , plasmid , biochemistry , biology , gene , physics , condensed matter physics , receptor , virulence
Lipid bilayer experiments were performed with chromosome‐encoded haemolysin of Escherichia coli . The addition of the toxin to the aqueous phase bathing lipid bilayer membranes of asolectin resulted in the formation of transient ion‐permeable channels with two states at small transmembrane voltages. One is prestate (single‐channel conductance 40 pS in 0.15 M KCl) of the open state, which had a single‐channel conductance of 420 pS in 0.15 M KCl and a mean lifetime of 30 s. Membranes formed of pure lipids were rather inactive targets for this haemolysin. Experiments with different salts suggested that the haemolysin channel was highly cation‐selective at neutral pH. The mobility sequence of the cations in the channel was similar if not identical to their mobility sequence in the aqueous phase. The single‐channel data were consistent with a wide, water‐filled channel with an estimated minimal diameter of about 1 nm. The pore‐forming properties of chromosome‐encoded haemolysin were compared with those of plasmid‐encoded haemolysin. Both toxins share common features, oligomerize probably to form pores in lipid bilayer membranes. Both types of haemolysin channels have similar properties but different lifetimes.