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Urea denaturation of α‐hemolysin pore inserted in planar lipid bilayer detected by single nanopore recording: Loss of structural asymmetry
Author(s) -
Pastoriza-Gallego Manuela,
Oukhaled Ghani,
Mathé Jérôme,
Thiebot Bénédicte,
Betton Jean-Michel,
Auvray Loïc,
Pelta Juan
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.06.036
Subject(s) - lipid bilayer , denaturation (fissile materials) , urea , bilayer , biophysics , chemistry , nanopore , hemolysin , monomer , crystallography , membrane , biochemistry , chromatography , analytical chemistry (journal) , materials science , nuclear chemistry , nanotechnology , organic chemistry , biology , virulence , gene , polymer
The aim of this work is to study pore protein denaturation inside a lipid bilayer and to probe current asymmetry as a function of the channel conformation. We describe the urea denaturation of α‐hemolysin channel and the channel formation of α‐hemolysin monomer incubated with urea prior to insertion into a lipid bilayer. Analysis of single‐channel recordings of current traces reveals a sigmoid curve of current intensity as a function of urea concentration. The normalized current asymmetry at 29 ± 4% is observed between 0 and 3.56 M concentrations and vanishes abruptly down to 0 concentration exceeds 4 M. The loss of current asymmetry through α‐hemolysin is due to the denaturation of the channel's cap. We also show that the α‐hemolysin pore inserted into a lipid bilayer is much more resistant to urea denaturation than the α‐hemolysin monomer in solution: The pore remains in the lipid bilayer up to 7.2 M urea. The pore formation is possible up to 4.66 M urea when protein monomers were previously incubated in urea.