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Single-Molecule Imaging of Lateral Mobility and Ion Channel Activity in Lipid Bilayers using Total Internal Reflection Fluorescence TIRF Microscopy
Published on: February 17, 2023
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Las fluctuaciones del potencial transitorio inducidas por iones facilitan la formación de poros y el transporte de
David Roesel1, Maksim Eremchev1, Chetan S Poojari2
1Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Journal of the American Chemical Society
|December 15, 2022
Resumen
Las fluctuaciones del potencial de membrana impulsan el transporte no asistido de iones al facilitar la formación de poros transitorios en las bicapas lipídicas. Este descubrimiento revela un nuevo mecanismo para el movimiento de iones crucial para las funciones celulares.
Área de la Ciencia:
- La biofísica
- Biología celular
- Ciencia de las membranas
Sus antecedentes:
- El transporte de iones sin ayuda a través de las membranas lipídicas es vital para las funciones celulares.
- Los mecanismos moleculares exactos que rigen este proceso no se comprenden completamente debido a la complejidad.
Objetivo del estudio:
- Establecer un vínculo directo entre las fluctuaciones del potencial de membrana y el transporte de iones divalentes.
- Para dilucidar el mecanismo de transporte de iones sin asistencia a través de las bicapas de lípidos.
Principales métodos:
- Se utilizó microscopía de segundo armónico no resonante de campo amplio de alto rendimiento (SH) para observar el agua de la membrana.
- Empleó simulaciones de dinámica molecular para analizar las variaciones de potencial de membrana y la formación de poros.
- El transporte de iones divalentes (Cu2 +, Ca2 +, Ba2 +, Mg2 +) experimentalmente fotografiado a través de las membranas de la vesícula unilamellar gigante (GUV).
Principales resultados:
- Se ha demostrado la presencia universal de fluctuaciones del potencial de membrana en los sistemas de dos capas lipídicas.
- Reveló que las fluctuaciones potenciales reducen la barrera de energía para la formación de poros transitorios.
- Mostró un aumento del flujo iónico a través de estos poros transitorios, confirmado por imágenes SH de cationes divalentes.
Conclusiones:
- Los poros transitorios, facilitados por campos electrostáticos inducidos por iones, sirven como conductos para el transporte de iones sin asistencia.
- Las fluctuaciones del potencial de membrana son un factor clave que permite la permeación iónica a través de las bicapas lipídicas.
- Este estudio proporciona un mecanismo viable para el transporte de iones sin asistencia, crucial para comprender la función celular.
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