Conformational dynamics in TRPV1 channels reported by an encoded coumarin amino acid
| Autor: | León D. Islas, Deny Cabezas-Bratesco, Ernesto Ladron de Guevara, Sebastian Brauchi, Federica Villa, Ximena Steinberg, Vincenzo Carnevale, Jason D. Galpin, Christopher A. Ahern, Marina A. Kasimova |
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| Rok vydání: | 2017 |
| Předmět: |
Models
Molecular 0301 basic medicine Intravital Microscopy Protein Conformation Structural Biology and Molecular Biophysics non-canonical amino acids Gating coumarin 01 natural sciences Molecular dynamics Transient receptor potential channel computational biology Protein structure Coumarins biophysics Biology (General) 0303 health sciences sezele Chemistry General Neuroscience General Medicine Fluorescence SPAD Biochemistry gating Medicine Research Article Computational and Systems Biology QH301-705.5 Science TRPV1 TRPV Cation Channels Total internal reflection microscopy Molecular Dynamics Simulation Stimulus (physiology) 010402 general chemistry General Biochemistry Genetics and Molecular Biology 03 medical and health sciences None Humans Ion channel 030304 developmental biology Total internal reflection fluorescence microscope Staining and Labeling General Immunology and Microbiology sezele SPAD TRPV1 biophysics computational biology coumarin gating non-canonical amino acids 0104 chemical sciences HEK293 Cells 030104 developmental biology Microscopy Fluorescence Structural biology Helix Biophysics Tyrosine Capsaicin pore |
| Zdroj: | eLife, Vol 6 (2017) eLife |
| ISSN: | 2050-084X |
| DOI: | 10.7554/elife.28626 |
| Popis: | TRPV1 channels support the detection of noxious and nociceptive input. Currently available functional and structural data suggest that TRPV1 channels have two gates within their permeation pathway: one formed by a ′bundle-crossing′ at the intracellular entrance and a second constriction at the selectivity filter. To describe conformational changes associated with channel gating, the fluorescent non-canonical amino acid coumarin-tyrosine was genetically encoded at Y671, a residue proximal to the selectivity filter. Total internal reflection fluorescence microscopy was performed to image the conformational dynamics of the channels in live cells. Photon counts and optical fluctuations from coumarin encoded within TRPV1 tetramers correlates with channel activation by capsaicin, providing an optical marker of conformational dynamics at the selectivity filter. In agreement with the fluorescence data, molecular dynamics simulations display alternating solvent exposure of Y671 in the closed and open states. Overall, the data point to a dynamic selectivity filter that may serve as a gate for permeation. eLife digest Cells use proteins on their surface as sensors to help them to assess and explore their environments and adapt to external conditions. The transient receptor potential (TRP) ion channels form one such family of proteins. Sodium, potassium and calcium ions can move through TRP channels to enter and exit cells, and by doing so trigger changes in the cell that help it respond to an external stimulus. The channels have physical “gates” that can open and close to control the flow of the ions. When the TRP channel detects a stimulus – which could take the form of specific chemicals, or a change in temperature, pressure or voltage – it changes shape, causing the gate to open. Researchers have a number of unanswered questions about how TRP channels work. Where in the channels are gates located? How do the channels control the flow of ions, and how do they communicate with each other? And which regions of the protein sense environmental cues? As a result, new technologies are being developed to make it easier to study the types of rearrangements that TRP channels experience when they activate. Steinberg, Kasimova et al. have used total internal reflection microscopy – a method that images fluorescent molecules – to measure the conformational change of a single TRP channel in a living cell. This channel, called TRPV1, senses external heat and plays an important role in pain perception. Its gate can also be opened by the pungent compound of chili pepper, capsaicin. The results of the experiments suggest that a selectivity filter region in TRPV1 channels changes its shape when the channel opens in response to capsaicin. Then, this selectivity filter appears to do double duty – it controls which types of ions pass through the channels as well as controlling their flow rate. Because of its role in pain perception, having a better understanding of how TRPV1 works will be valuable for researchers who are trying to develop new pain relief treatments. The so-called ‘seeing is believing’ method used by Steinberg, Kasimova et al. could also be used to study other membrane proteins, both to guide drug development and to improve our understanding of how cells interact with their environment. |
| Databáze: | OpenAIRE |
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