Surface Changes of the Mechanosensitive Channel MscS upon Its Activation, Inactivation, and Closing
| Autor: | Andrzej Kubalski, Piotr Koprowski, Wojciech Grajkowski |
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| Rok vydání: | 2005 |
| Předmět: |
Models
Molecular Cytoplasm Time Factors Protein Conformation Surface Properties Biophysics Thermal fluctuations Plasma protein binding Mechanotransduction Cellular Ion Channels Polyethylene Glycols Protein structure Escherichia coli Pressure Ficoll Mechanotransduction Protein Structure Quaternary Ion channel Chemistry Escherichia coli Proteins Protoplasts Proteins Dextrans Electrophysiology Glucose Biochemistry Mechanosensitive channels Ion Channel Gating Communication channel Protein Binding |
| Zdroj: | Biophysical Journal. 88(4):3050-3059 |
| ISSN: | 0006-3495 |
| DOI: | 10.1529/biophysj.104.053546 |
| Popis: | MscS is a bacterial mechanosensitive channel that shows voltage dependence. The crystal structure of MscS revealed that the channel is a homoheptamer with a large chamber on the intracellular site. Our previous experiments indicated that the cytoplasmic chamber of the channel is not a rigid structure and changes its conformation upon the channel activation. In this study, we have applied various sized cosolvents that are excluded from protein surfaces. It is well known that such cosolvents induce compaction of proteins and prevent thermal fluctuations. It is also known that they shift channel equilibrium to the state of lower volume. We have found that large cosolvents that cannot enter the channel interior accelerate channel inactivation when applied from the cytoplasmic side, but they slow down inactivation when applied from the extracellular side. We have also found that small cosolvents that can enter the channel cytoplasmic chamber prevent the channel from opening, unlike the large ones. These data support our idea that the channel cytoplasmic chamber shrinks upon inactivation but also give new clues about conformational changes of the channel upon transitions between its functional states. |
| Databáze: | OpenAIRE |
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