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| Open AccessExtracellular modulation of TREK-2 activity with nanobodies provides insight into the mechanisms of K2P channel regulation
K2P channels are important regulators of cellular electrical activity. Here the authors show how nanobody fragments can be used to detect and modulate TREK2 K2P channel activity to provide insight into the mechanism of gating.
- Karin E. J. Rödström
- , Alexander Cloake
- & Stephen J. Tucker
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Article
| Open AccessInterplay between Mg2+ and Ca2+ at multiple sites of the ryanodine receptor
Skeletal ryanodine receptor controls calcium mobilization indispensable for muscle contraction. Here, authors combine cryo-EM and molecular dynamics to uncover the structural basis of the intricate regulation of this channel by calcium and magnesium.
- Ashok R. Nayak
- , Warin Rangubpit
- & Montserrat Samsó
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Article
| Open AccessStructural insights into drug transport by an aquaglyceroporin
Pentamidine and melarsoprol are drugs used to treat sleeping sickness caused by Trypanosoma brucei. Here, authors present cryo-EM structures of TbAQP2 with molecular dynamic simulations, revealing mechanisms shaping substrate specificity and drug permeation.
- Wanbiao Chen
- , Rongfeng Zou
- & Chongyuan Wang
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Article
| Open AccessStructural basis and synergism of ATP and Na+ activation in bacterial K+ uptake system KtrAB
KtrAB complex is essential in K+ uptake for bacteria. Here authors illustrate the synergism of ATP and Na+ in activating K+ uptake of KtrAB from Bacillus subtilis and its gating mechanism, which may also shed light on other Na+-activated K+ channels.
- Wesley Tien Chiang
- , Yao-Kai Chang
- & Nien-Jen Hu
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Article
| Open AccessMechanistic basis of the dynamic response of TWIK1 ionic selectivity to pH
Using computer simulations authors identify the dynamic molecular motions controlling the structural conformation of the TWIK1 ion channel, showing that its ability to transport sodium upon acidification result from the evolution of the classical potassium-selective pore.
- Franck C. Chatelain
- , Nicolas Gilbert
- & Olivier Bignucolo
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Article
| Open AccessGalectin-3 impairs calcium transients and β-cell function
Galectin-3, mainly produced and secreted by macrophages, is elevated in diabetes. Here, the authors show that galectin-3 directly interacts with voltage-gated channel auxiliary subunit gamma 1 (CACNG1) and blocks calcium transients and subsequent insulin secretion.
- Qian Jiang
- , Qijin Zhao
- & Pingping Li
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Article
| Open AccessTension activation of mechanosensitive two-pore domain K+ channels TRAAK, TREK-1, and TREK-2
TRAAK, TREK-1 and TREK-2 are mechanosensitive potassium channels involved in action potential propagation among other roles. Here, authors quantify their tension response and show ultrasound can generate tension to activate ion channels.
- Ben Sorum
- , Trevor Docter
- & Stephen G. Brohawn
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Article
| Open AccessCryo-EM structures of pannexin 1 and 3 reveal differences among pannexin isoforms
Pannexins are large pore channels involved in ion and ATP release. Here the authors use cryo-EM structures of Pannexins 1 and 3 to demonstrate the effects of distinct residue substitutions on channel structure and function.
- Nazia Hussain
- , Ashish Apotikar
- & Aravind Penmatsa
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Article
| Open AccessStructural bases of inhibitory mechanism of CaV1.2 channel inhibitors
CaV1.2 is crucial in cardiac, vascular and neuronal function, serving as a target for many drugs. Here, authors identify the binding site of herb-derived drug tetrandrine, and explore inhibitory mechanism of L/T-type selective DHP drug benidipine.
- Yiqing Wei
- , Zhuoya Yu
- & Yan Zhao
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Article
| Open AccessThe binding and mechanism of a positive allosteric modulator of Kv3 channels
To promote the development of effective small molecule modulators that may help treat diverse neuropsychiatric disorders, this study elucidates the mechanism of a specific positive modulator of neuronal potassium channels at near-atomic resolution.
- Qiansheng Liang
- , Gamma Chi
- & Manuel Covarrubias
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Article
| Open AccessStructure of an open KATP channel reveals tandem PIP2 binding sites mediating the Kir6.2 and SUR1 regulatory interface
KATP channels regulate insulin secretion and are activated by PIP2. Here, the authors show PIP2 binds between SUR1 and Kir6.2 to open the channel, and a neonatal diabetes mutation stabilizes KATP channels in a PIP2-bound open conformation.
- Camden M. Driggers
- , Yi-Ying Kuo
- & Show-Ling Shyng
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Article
| Open AccessDual receptor-sites reveal the structural basis for hyperactivation of sodium channels by poison-dart toxin batrachotoxin
The poison dart toxin batrachotoxin is the most lethal voltage-gated sodium channel toxin. Here authors identify the toxin bound specifically at two homologous receptor sites, which cause channel hyperactivation by positively modulating channel gating and altering ion conductance.
- Lige Tonggu
- , Goragot Wisedchaisri
- & William A. Catterall
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Article
| Open AccessChloride intracellular channel (CLIC) proteins function as fusogens
The Chloride Intracellular Channel (CLIC) protein family is highly conserved, yet their function remains a matter of ongoing research. Here, authors reveal their ability to facilitate membrane fusion, shedding light on their physiological role.
- Bar Manori
- , Alisa Vaknin
- & Yoni Haitin
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Article
| Open AccessA release of local subunit conformational heterogeneity underlies gating in a muscle nicotinic acetylcholine receptor
Authors show that agonist binding to the muscle acetylcholine receptor releases local conformational heterogeneity transitioning all subunits into a symmetric open state. A release of conformational heterogeneity underlies allosteric communication.
- Mackenzie J. Thompson
- , Farid Mansoub Bekarkhanechi
- & John E. Baenziger
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Article
| Open AccessPhotolipid excitation triggers depolarizing optocapacitive currents and action potentials
Inspired by thermal optocapacitive approaches at regulating neuronal activity, the authors explore a photolipid-based non-thermal optocapacitive method that allows for regulating voltage-gated and mechanosensitive ion channels using light.
- Carlos A. Z. Bassetto Jr
- , Juergen Pfeffermann
- & Peter Pohl
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Article
| Open AccessA high affinity switch for cAMP in the HCN pacemaker channels
Cyclic AMP modulation of HCN channels underlies beta adrenergic stimulation of heart rate. Here, authors describe an intramolecular mechanism that controls cAMP affinity of the cyclic nucleotide binding domain of these channels.
- Alessandro Porro
- , Andrea Saponaro
- & Anna Moroni
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Article
| Open AccessLipid nanodisc scaffold and size alter the structure of a pentameric ligand-gated ion channel
The authors show that lipid nanodiscs of different scaffold type and size alter the structure of the pentameric ligand-gated ion channel, ELIC. The results suggest that nanodisc selection is an important consideration for structural studies of membrane proteins.
- Vikram Dalal
- , Mark J. Arcario
- & Wayland W. L. Cheng
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Article
| Open AccessSelective blockade of Cav1.2 (α1C) versus Cav1.3 (α1D) L-type calcium channels by the black mamba toxin calciseptine
L-type voltage-gated calcium channels are involved in multiple physiological functions. Here the authors identify calciseptine, a toxin purified from black mamba venom, as a selective inhibitor of Cav1.2 L-type Ca2+ channels.
- Pietro Mesirca
- , Jean Chemin
- & Joël Nargeot
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Article
| Open AccessVoltage sensors of a Na+ channel dissociate from the pore domain and form inter-channel dimers in the resting state
It is believed that voltage sensor domains (VSD) of voltage-gated Na+ channels are always attached to the channel. Here, authors find that VSDs detach from the channel to form inter-channel dimers.
- Ayumi Sumino
- , Takashi Sumikama
- & Katsumasa Irie
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Article
| Open AccessElucidation of the structural basis for ligand binding and translocation in conserved insect odorant receptor co-receptors
Insects rely on olfaction for behavior control. Recent structural studies of receptors provide insight into ligand binding. Here, the authors identify dynamic binding mechanism to Orco, explaining its high selectivity with insights in compound screening.
- Jody Pacalon
- , Guillaume Audic
- & Jérémie Topin
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Article
| Open AccessStructural and functional insights into the delivery of a bacterial Rhs pore-forming toxin to the membrane
Bacterial Rhs proteins constitute a diverse family of secreted toxins. Here, the authors present a cryo-electron microscopy structure of an Rhs protein from Pseudomonas aeruginosa and provide insights into the mechanisms by which the protein delivers its encapsulated pore-forming toxin fragment to the bacterial membrane.
- Amaia González-Magaña
- , Igor Tascón
- & David Albesa-Jové
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Article
| Open AccessMechanically-primed voltage-gated proton channels from angiosperm plants
The authors describe a proton channel protein in the vasculature of Arabidopsis thaliana that requires both mechanical and electrical stimuli to turn on. A mechanistic analysis identifies the molecular determinants for the hybrid activation process.
- Chang Zhao
- , Parker D. Webster
- & Francesco Tombola
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Article
| Open AccessCryo-EM structures of the plant anion channel SLAC1 from Arabidopsis thaliana suggest a combined activation model
Phosphorylation-mediated activation of SLAC1 anion channel is crucial in plant responses for abiotic stresses including drought. Here, authors determine the open and closed structures of SLAC1, revealing how phosphorylation can activate SLAC1.
- Yeongmok Lee
- , Hyeon Seong Jeong
- & Sangho Lee
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Article
| Open AccessCryo-EM structure of TMEM63C suggests it functions as a monomer
TMEM63s are mechanosensitive ion channels activated by hypo-osmolality. Here, the authors determine the cryo-EM structure of mouse TMEM63C confirming its predominant monomeric state and the significance of TM0-TM6 coupling in channel activity.
- Yuqi Qin
- , Daqi Yu
- & Shangyu Dang
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Article
| Open AccessProgesterone activation of β1-containing BK channels involves two binding sites
Progesterone is used in recovery of cerebral ischemia however the mechanism of action is unknown. Authors report here that micromolar progesterone activates mouse cerebrovascular myocyte BK channels, involving two steroid binding sites.
- Kelsey C. North
- , Andrew A. Shaw
- & Alex M. Dopico
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Article
| Open AccessCryo-EM structures of human magnesium channel MRS2 reveal gating and regulatory mechanisms
Magnesium homeostasis is key for cellular functions. Here, authors report structures of human mitochondrial Mg2+ channel MRS2 and identified key residues in gating. This work provides insights into the gating and regulatory mechanisms of MRS2.
- Louis Tung Faat Lai
- , Jayashree Balaraman
- & Doreen Matthies
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Article
| Open AccessAn apical Phe-His pair defines the Orai1-coupling site and its occlusion within STIM1
The intermembrane complexes mediating calcium signals are crucial but poorly understood. Here the authors identify a Phe-His pair in the calcium-sensing STIM1 protein that controls both activation and pairing of STIM1 with Orai channels to generate calcium signals
- Yandong Zhou
- , Michelle R. Jennette
- & Donald L. Gill
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Article
| Open AccessStructural titration reveals Ca2+-dependent conformational landscape of the IP3 receptor
Inositol 1,4,5-trisphosphate receptors (IP3Rs) are intracellular Ca2+ channels that produce Ca2+ oscillations in response to GPCR and RTK activation. Here, Paknejad et al. resolve the conformational landscape of IP3Rs that gives rise to the biphasic dependence on Ca2+ for channel activity.
- Navid Paknejad
- , Vinay Sapuru
- & Richard K. Hite
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Article
| Open AccessGSG1L-containing AMPA receptor complexes are defined by their spatiotemporal expression, native interactome and allosteric sites
TARPs and GSG1L are evolutionarily- and structurally-related AMPA receptor auxiliary subunits that differ in function through unresolved mechanisms. Here, the authors provide insight into the spatiotemporal expression, composition, and functionality of GSG1L-containing protein complexes.
- Amanda M. Perozzo
- , Jochen Schwenk
- & Derek Bowie
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Article
| Open AccessLigand activation mechanisms of human KCNQ2 channel
The potassium channel KCNQ2 can be activated by analgesics and antiepileptic drugs via an unclear mechanism. Here authors report structures of KCNQ2-CaM in complex with cannabidiol, PIP2, and HN37 and elucidate the mechanisms of activation.
- Demin Ma
- , Yueming Zheng
- & Jiangtao Guo
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Article
| Open AccessDirect regulation of the voltage sensor of HCN channels by membrane lipid compartmentalization
Voltage sensing of ion channels relies on charged transmembrane helices. Here authors use live-cell FLIM-FRET and nonsense suppression-mediated fluorescence labeling to reveal that voltage sensors undergo direct modulation by compartmentalized membrane domains.
- Lucas J. Handlin
- & Gucan Dai
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Article
| Open AccessStructural insights into the allosteric inhibition of P2X4 receptors
Cryo-EM structures revealed how chemical compounds bind to and inhibit P2X4 receptors involved in neuropathic pain, potentially facilitating the design of drugs targeting P2X4 receptors.
- Cheng Shen
- , Yuqing Zhang
- & Motoyuki Hattori
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Article
| Open AccessAsymmetric gating of a human hetero-pentameric glycine receptor
Despite essential roles in adult nervous systems, how heteromeric Cys-loop receptors work is unclear in the absence of an open state structure. Here, the authors report closed/open state structures and functional experiments, detailing an asymmetric gating mechanism driven by differing contributions from each subunit type.
- Xiaofen Liu
- & Weiwei Wang
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Article
| Open AccessStructural basis of the activation of TRPV5 channels by long-chain acyl-Coenzyme-A
Long-chain acyl-Coenzyme-A is a metabolic intermediate with important signaling functions. Here the authors show that it activates the Ca2+ selective ion channels TRPV5 and TRPV6 and elucidate the structural basis of TRPV5 activation using CryoEM.
- Bo-Hyun Lee
- , José J. De Jesús Pérez
- & Tibor Rohacs
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Article
| Open AccessChronic cough relief by allosteric modulation of P2X3 without taste disturbance
P2X3 activation requires tightening the inner pocket of the head domain (IP-HD) following ATP binding. Here the authors demonstrate that targeting the IP-HD with allosteric small molecules presents a potential strategy for the development of therapeutics for refractory chronic cough without taste abnormalities.
- Chang-Run Guo
- , Zhong-Zhe Zhang
- & Ye Yu
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Article
| Open AccessDNA nanopores as artificial membrane channels for bioprotonics
Synthetic membrane channels have many potential applications, but interfacing membrane channels with electronic devices for efficient information transfer is challenging. Here the authors integrate membrane spanning DNA nanopores with bioprotonic contacts to create programmable, modular, and efficient artificial ion-channel interfaces.
- Le Luo
- , Swathi Manda
- & Marco Rolandi
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Article
| Open AccessStructural insights into opposing actions of neurosteroids on GABAA receptors
Legesse et al. present structural studies of a human GABAA receptor in complex with positive and negative modulator neurosteroids, uncovering mechanisms of potentiation and inhibition.
- Dagimhiwat H. Legesse
- , Chen Fan
- & Ryan E. Hibbs
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Article
| Open AccessA mechanistic reinterpretation of fast inactivation in voltage-gated Na+ channels
Here, authors have identified two pairs of large hydrophobic residues in the channel S6 segments that form the inactivation gate of eukaryotic Na+ channels.
- Yichen Liu
- , Carlos A. Z. Bassetto Jr
- & Francisco Bezanilla
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Article
| Open AccessIdentification of a drug binding pocket in TMEM16F calcium-activated ion channel and lipid scramblase
TMEM16F is a Ca2+ activated ion channel and lipid scramblase involved in cell fusion. Here authors determine cryo-EM structures of TMEM16F with or without bound blockers, such as the FDA-approved drug niclosamide.
- Shengjie Feng
- , Cristina Puchades
- & Lily Yeh Jan
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Article
| Open AccessCryo-EM structures of human zinc transporter ZnT7 reveal the mechanism of Zn2+ uptake into the Golgi apparatus
ZnT7 is a Golgi-localized Zn2 + /H+ antiporter. Here the authors present the cryo-EM structures of human ZnT7 in Zn2 + -bound and unbound forms, shedding light on its mechanism of Zn2+ transport.
- Han Ba Bui
- , Satoshi Watanabe
- & Kenji Inaba
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Article
| Open AccessMolecular pathway and structural mechanism of human oncochannel TRPV6 inhibition by the phytocannabinoid tetrahydrocannabivarin
Neuberger et al. report the structure of human channel TRPV6 in complex with a cannabinoid inhibitor tetrahydrocannabivarin (THCV) and explore the pathway taken by the drug to reach binding sites in the portals that connect the membrane environment to the central cavity of the ion channel pore.
- Arthur Neuberger
- , Yury A. Trofimov
- & Alexander I. Sobolevsky
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Article
| Open AccessSubunit gating resulting from individual protonation events in Kir2 channels
Here, authors introduced negative charges in the transmembrane helices in Kir2.2 channels generating pH-dependent sub-conductances. Molecular dynamics simulations show how protonation results in step-wise alterations of ion pooling and hence conductance, appearing as gated substates.
- Grigory Maksaev
- , Michael Bründl-Jirout
- & Colin G. Nichols
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Article
| Open AccessCysteines 1078 and 2991 cross-linking plays a critical role in redox regulation of cardiac ryanodine receptor (RyR)
Oxidation of ryanodine receptor calcium channels play a critical role in the onset of many cardiac diseases. Here, authors identify specific amino acids that cause ryanodine receptor malfunction during oxidative stress.
- Roman Nikolaienko
- , Elisa Bovo
- & Aleksey V. Zima
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Article
| Open AccessConformational trajectory of allosteric gating of the human cone photoreceptor cyclic nucleotide-gated channel
Hu et al. present eight cryo-EM structures of the human cone photoreceptor CNGA3/CNGB3 channel in the closed, intermediate, pre-open and open states, all fully bound with cGMP. These structures provide an unprecedented view of the conformational trajectory of CNG channel activation.
- Zhengshan Hu
- , Xiangdong Zheng
- & Jian Yang
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Article
| Open AccessThe structural basis of divalent cation block in a tetrameric prokaryotic sodium channel
Divalent cation block is observed in various tetrameric ion channels. Here, authors use X-ray crystallography, electrophysiology and molecular dynamics simulations to reveal the mechanism of the divalent cation block on a prokaryotic sodium channel.
- Katsumasa Irie
- , Yoshinori Oda
- & Yoshinori Fujiyoshi
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Article
| Open AccessCrosstalk between regulatory elements in disordered TRPV4 N-terminus modulates lipid-dependent channel activity
An integrated structural biology approach uncovers the structural complexity of the intrinsically disordered region (IDR) within the TRPV4 ion channel. Multiple stimulatory and inhibitory elements were identified within the IDR that modulate channel activity in a lipid-dependent manner.
- Benedikt Goretzki
- , Christoph Wiedemann
- & Ute A. Hellmich
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Article
| Open AccessA mechanical-coupling mechanism in OSCA/TMEM63 channel mechanosensitivity
Mechanosensitive channels exhibit large structural variations. Here, the authors reveal that OSCA channels exhibit different oligomeric states and are gated/regulated by lipids at different locations in response to physical forces.
- Mingfeng Zhang
- , Yuanyue Shan
- & Duanqing Pei
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Article
| Open AccessStructure of human CALHM1 reveals key locations for channel regulation and blockade by ruthenium red
The voltage-dependent CALHM1 channel is critical in neuromodulation and gustatory signaling. The authors present cryo-EM structures of human CALHM1 in apo- and blocked-states. They explore effects of lipid binding on channel structure and activity.
- Johanna L. Syrjänen
- , Max Epstein
- & Hiro Furukawa
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Article
| Open AccessTRPV4-Rho GTPase complex structures reveal mechanisms of gating and disease
Despite TRPV4’s medical importance, the mechanisms of ligand-mediated channel gating and its regulation by Rho GTPase are unclear. Here, the authors report the structures of TRPV4 in complex with RhoA and ligands, offering atomic-level insights into their functions.
- Do Hoon Kwon
- , Feng Zhang
- & Seok-Yong Lee