Chemical rescue of histidine selectivity filter mutants of the M2 ion channel of influenza A virus
| Autor: | Padmavati Venkataraman, Robert A. Lamb, Lawrence H. Pinto |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Time Factors
Genotype Stereochemistry Morpholines Protonation Endosomes Buffers Biochemistry Models Biological Polymerase Chain Reaction Dissociation (chemistry) Viral Matrix Proteins Residue (chemistry) Xenopus laevis Proton transport Amantadine Animals Histidine RNA Messenger Molecular Biology Ion channel Ions biology Dose-Response Relationship Drug Chemistry Cell Membrane Imidazoles Tryptophan Cell Biology Hydrogen-Ion Concentration Kinetics M2 proton channel Alkanesulfonic Acids Microscopy Fluorescence Models Chemical Mutation biology.protein Oocytes Protons Sulfonic Acids Copper Homotetramer Protein Binding |
| Zdroj: | The Journal of biological chemistry. 280(22) |
| ISSN: | 0021-9258 |
| Popis: | The influenza virus M2 proton-selective ion channel activity facilitates virus uncoating, a process that occurs in the acidic environment of the endosome. The M2 channel causes acidification of the interior of the virus particle, which results in viral protein-protein dissociation. The M2 protein is a homotetramer that contains in its aqueous pore a histidine residue (His-37) that acts as a selectivity filter and a tryptophan residue (Trp-41) that acts as a channel gate. Substitution of His-37 modifies M2 ion channel properties drastically. However, the results of such experiments are difficult to interpret because substitution of His-37 could cause gross structural changes to the channel pore. We described here experiments in which partial or, in some cases, full rescue of specific M2 ion channel properties of His-37 substitution mutants was achieved by addition of imidazole to the bathing medium. Chemical rescue was demonstrated for three histidine substitution mutant ion channels (M2-H37G, M2-H37S, and M2-H37T) and for two double mutants in which the Trp-41 channel gate was also mutated (H37G/W41Y and H37G/W41A). Currents of the M2-H37G mutant ion channel were inhibited by Cu(II), which has been shown to coordinate with His-37 in the wild-type channel. Chemical rescue was very specific for imidazole. Buffer molecules that were neutral when protonated (4-morpholineethanesulfonic acid and 3-morpholino-2-hydroxypropanesulfonic acid) did not rescue ion channel activity of the M2-H37G mutant ion channel, but 1-methylimidazole did provide partial rescue of function. These results were consistent with a model for proton transport through the pore of the wild-type channel in which the imidazole side chain of His-37 acted as an intermediate proton acceptor/donor group. |
| Databáze: | OpenAIRE |
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