Back to Search
Start Over
Blockage of anthrax PA63 pore by a multicharged high-affinity toxin inhibitor.
- Source :
-
Biophysical journal [Biophys J] 2010 Jul 07; Vol. 99 (1), pp. 134-43. - Publication Year :
- 2010
-
Abstract
- Single channels of Bacillus anthracis protective antigen, PA(63), were reconstituted into planar lipid membranes and their inhibition by cationic aminopropylthio-beta-cyclodextrin, AmPrbetaCD, was studied. The design of the highly efficient inhibitor, the sevenfold symmetrical cyclodextrin molecule chemically modified to add seven positive charges, was guided by the symmetry and predominantly negative charge of the PA(63) pore. The protective action of this compound has been demonstrated earlier at both single-molecule and whole-organism levels. In this study, using noise analysis, statistics of time-resolved single-channel closure events, and multichannel measurements, we find that AmPrbetaCD action is bimodal. The inhibitor, when added to the cis side of the membrane, blocks the channel reversibly. At high salt concentrations, the AmPrbetaCD blockage of the channel is well described as a two-state Markov process, in which both the on- and off-rates are functions of the salt concentration, whereas the applied voltage affects only the off-rate. At salt concentrations smaller than 1.5 M, the second mode of AmPrbetaCD action on the channel is discovered: addition of the inhibitor enhances voltage gating, making the closed states of the channel more favorable. The effect depends on the lipid composition of the membrane.<br /> (Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.)
- Subjects :
- Antigens, Bacterial chemistry
Bacterial Toxins chemistry
Cell Membrane chemistry
Cell Membrane drug effects
Cell Membrane metabolism
Dose-Response Relationship, Drug
Electric Conductivity
Ion Channel Gating drug effects
Kinetics
Lipid Metabolism
Markov Chains
Models, Molecular
Porosity
Protein Binding
Protein Conformation
Antigens, Bacterial metabolism
Bacterial Toxins antagonists & inhibitors
Bacterial Toxins metabolism
beta-Cyclodextrins metabolism
beta-Cyclodextrins pharmacology
Subjects
Details
- Language :
- English
- ISSN :
- 1542-0086
- Volume :
- 99
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biophysical journal
- Publication Type :
- Academic Journal
- Accession number :
- 20655841
- Full Text :
- https://doi.org/10.1016/j.bpj.2010.03.070