Crystal structure and dynamics of a lipid-induced potential desensitized-state of a pentameric ligand-gated channel

Basak, Sandip; Schmandt, Nicolaus; Gicheru, Yvonne; Chakrapani, Sudha

doi:10.7554/elife.23886

Cited by 72 publications

(106 citation statements)

References 124 publications

(204 reference statements)

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“…10A and B). Incidentally, such an experiment has been performed, and DHA pre-application is indeed shown to elicit robust inhibition of the GLIC peak response elicited by protons (Basak et al 2017), consistent with DHA affecting a pre-activation step. Moreover, with simple linear schemes as the ones presented here, and if we assume that desensitization kinetics remain slower than activation kinetics, the agonist concentration-response curve for peak responses should not be affected by a drug modulating desensitization.…”

Section: Reconciling the Docosahexaenoic Acid-bound Structure Of Glicmentioning

confidence: 78%

“…The DHA‐induced increase in apparent affinity for protons, as measured with peak responses (Basak et al . ), is thus another argument in favour of DHA modulating the pre‐activation step (Fig. F ).…”

Section: Introductionmentioning

confidence: 90%

“…These results do not agree with the DHA‐bound structure representing a desensitized state, since the M4 segments are superimposable in the DHA‐bound and in the putative open and resting states of GLIC (Basak et al . ). Thus, the DHA‐bound structure may well represent an intermediate pre‐active shut state, and this interesting one‐of‐a‐kind structure could help in delineating the activation transition pathway of pLGICs.…”

Section: Introductionmentioning

confidence: 97%

“…Recently, an X‐ray structure of the bacterial pLGIC GLIC in complex with the fatty acid docosahexaenoic acid (DHA) revealed a new pore conformation, with a profile intermediate between that of the putative resting and open states of the channel (Basak et al . ): the activation gate has transitioned towards the open channel conformation, with the exception of the M2 9′ residue that still shapes a hydrophobic constriction in the middle of the pore.…”

Section: Introductionmentioning

confidence: 99%

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The dual‐gate model for pentameric ligand‐gated ion channels activation and desensitization

Gielen

Corringer

2018

The Journal of Physiology

115

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Pentameric ligand-gated ion channels (pLGICs) mediate fast neurotransmission in the nervous system. Their dysfunction is associated with psychiatric, neurological and neurodegenerative disorders such as schizophrenia, epilepsy and Alzheimer's disease. Understanding their biophysical and pharmacological properties, at both the functional and the structural level, thus holds many therapeutic promises. In addition to their agonist-elicited activation, most pLGICs display another key allosteric property, namely desensitization, in which they enter a shut state refractory to activation upon sustained agonist binding. While the activation mechanisms of several pLGICs have been revealed at near-atomic resolution, the structural foundation of desensitization has long remained elusive. Recent structural and functional data now suggest that the activation and desensitization gates are distinct, and are located at both sides of the ion channel. Such a 'dual gate mechanism' accounts for the marked allosteric effects of channel blockers, a feature illustrated herein by theoretical kinetics simulations. Comparison with other classes of ligand- and voltage-gated ion channels shows that this dual gate mechanism emerges as a common theme for the desensitization and inactivation properties of structurally unrelated ion channels.

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Section: Reconciling the Docosahexaenoic Acid-bound Structure Of Glicmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The dual‐gate model for pentameric ligand‐gated ion channels activation and desensitization

Gielen

Corringer

2018

The Journal of Physiology

115

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“…EPR and double electron-electron resonance (DEER) spectroscopies have provided definitive mechanistic models for ion channels [30][31][32][33][34][35] , G protein-coupled receptors 36 , and transporters 37,38 . These techniques have been mainly restricted to the examination of bacterial channels that contain few (or none) cysteine residues that are not critical for protein function; this requirement has largely hampered the study of mammalian ion channels using these approaches.…”

mentioning

confidence: 99%

Expression and Purification of the Pain Receptor TRPV1 for Spectroscopic Analysis

Velisetty

Valdez

Vásquez

2018

Biophysical Journal

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The transient receptor potential vanilloid 1 (TRPV1) channel is an essential component of the cellular mechanism through which noxious stimuli evoke pain. Functional and structural characterizations of TRPV1 shed light on vanilloid activation, yet the mechanisms for temperature and proton gating remain largely unknown. Spectroscopic approaches are needed to understand the mechanisms by which TRPV1 translates diverse stimuli into channel opening. Here, we have engineered a minimal cysteine-less rat TRPV1 construct (eTRPV1) that can be stably purified and reconstituted for spectroscopic studies. Biophysical analyses of TRPV1 constructs reveal that the S5-pore helix loop influences protein stability and vanilloid and proton responses, but not thermal sensitivity. Cysteine mutants retain function and stability for double electron-electron resonance (DEER) and electron paramagnetic resonance (EPR) spectroscopies. DEER measurements in the closed state demonstrate that eTRPV1 reports distances in the extracellular vestibule, equivalent to those observed in the apo TRPV1 structure. EPR measurements show a distinct pattern of mobilities and spectral features, in detergent and liposomes, for residues at the pore domain that agree with their location in the TRPV1 structure. Our results set the stage for a systematic characterization of TRPV1 using spectroscopic approaches to reveal conformational changes compatible with thermal-and ligand-dependent gating.The detection of painful stimuli involves ion channels that depolarize sensory neurons to elicit or intensify inflammatory pain 1 . One such channel is the transient receptor potential vanilloid 1 (TRPV1) expressed by primary afferent sensory neurons, where it contributes to the mechanisms underlying pain hypersensitivity 2 . TRPV1 is a polymodal ion channel activated by noxious heat (>42 °C), the pungent ingredient of "hot" chili peppers (capsaicin) 3 , animal toxins 4-6 , extracellular protons 7 , and modulated by proalgesic inflammatory agents (e.g., bradykinin 8 , bioactive lipids 9, 10 ) produced in response to tissue injury. Because TRPV1 is an important therapeutic target 11 , it is crucial to determine the structural rearrangements that lead to channel opening by multiple stimuli. Functional and structural studies have provided insights into TRPV1 activation mechanisms by vanilloids and toxins 5,[12][13][14][15][16][17][18] . It is generally agreed that upon vanilloid binding, the interaction between capsaicin or resiniferatoxin [RTX] with the S4-S5 linker triggers rearrangements consistent with opening of the lower gate 14, 15 . Likewise, venom toxins (e.g., double knot toxin, DkTx) stabilize the open state by inserting hydrophobic residues into the membrane phospholipids and binding to the TRPV1 extracellular pore region 5,16,17 . Aside from vanilloids and toxins, acidification of the extracellular media can activate and/or potentiate TRPV1 responses to other stimuli 7,13 . For instance, the heat response is potentiated by extracellular protons within the pH ...

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Important amino acids for function of the insect Rdl GABA receptor

Nakao

Banba

2020

Pest Management Science

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BACKGROUND Insect Rdl GABA receptor is an important insecticide target. To design a novel insecticide, studies on the structures of homologous pentameric ligand‐gated ion channels provide information about important amino acids that are necessary for the function of insect Rdl GABA receptors. RESULTS L9'A, T12'A, T13'A, T13'S, M15'S, and M15′N mutations in the Drosophila Rdl GABA receptor subunit caused the protein to spontaneously adopt the open state conformation. In contrast, the S16'A, S16′T, S17'A, and S17′H mutant homomers showed the same levels of agonist and antagonist sensitivity as the wild‐type receptor. The G336M mutation in the Drosophila Rdl GABA receptor abolished the agonist activities of ivermectin and milbemectin, but the F339M mutation did not. Additionally, the F339M mutation caused spontaneous opening of the receptor. In the Drosophila Rdl model, the hydrophobic girdle plays an important role in stabilization of the closed state. Mutations which decrease hydrophobic interactions resulted in spontaneous opening, supporting the importance of the hydrophobic girdle for keeping the channel closed. Through a mutational study of transmembrane 3 (TM3) cytoplasmic domain and Rdl GABA receptor modeling, hydrophobic interactions between TM3 and TM4 and intersubunit interaction were demonstrated to be important for channel gating. Alternatively, the intrasubunit interaction between TM2 and TM3 domains were less important for channel gating in case of Drosophila Rdl GABA receptor. CONCLUSION This study demonstrates important amino acids critical to the function of the Drosophila Rdl GABA receptor based on the mutational studies and Drosophila Rdl GABA receptor modeling approach. © 2020 Society of Chemical Industry

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Crystal structure and dynamics of a lipid-induced potential desensitized-state of a pentameric ligand-gated channel

Cited by 72 publications

References 124 publications

The dual‐gate model for pentameric ligand‐gated ion channels activation and desensitization

The dual‐gate model for pentameric ligand‐gated ion channels activation and desensitization

Expression and Purification of the Pain Receptor TRPV1 for Spectroscopic Analysis

Important amino acids for function of the insect Rdl GABA receptor

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