Spatiotemporal Imaging of Water in Operating Voltage-Gated Ion Channels Reveals the Slow Motion of Interfacial Ions
| Autor: | Sylvie Roke, Aleksandra Radenovic, Maksim Yu. Eremchev, Orly B. Tarun |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Millisecond
Alamethicin Materials science Mechanical Engineering Bioengineering 02 engineering and technology General Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Ion chemistry.chemical_compound Membrane chemistry Chemical physics Molecule General Materials Science 0210 nano-technology Lipid bilayer Ion channel Ion transporter |
| Zdroj: | Nano Letters |
| ISSN: | 1530-6992 1530-6984 |
| Popis: | Ion channels are responsible for numerous physiological functions ranging from transport to chemical and electrical signaling. Although static ion channel structure has been studied following a structural biology approach, spatiotemporal investigation of the dynamic molecular mechanisms of operational ion channels has not been achieved experimentally. In particular, the role of water remains elusive. Here, we perform label-free spatiotemporal second harmonic (SH) imaging and capacitance measurements of operational voltage-gated alamethicin ion channels in freestanding lipid membranes surrounded by aqueous solution on either side. We observe changes in SH intensity upon channel activation that are traced back to changes in the orientational distribution of water molecules that reorient along the field lines of transported ions. Of the transported ions, a fraction of 10–4 arrives at the hydrated membrane interface, leading to interfacial electrostatic changes on the time scale of a second. The time scale of these interfacial changes is influenced by the density of ion channels and is subject to a crowding mechanism. Ion transport along cell membranes is often associated with the propagation of electrical signals in neurons. As our study shows that this process is taking place over seconds, a more complex mechanism is likely responsible for the propagation of neuronal electrical signals than just the millisecond movement of ions. |
| Databáze: | OpenAIRE |
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