Tightening of the ATP-binding sites induces the opening of P2X receptor channels

Jiang, Ruotian; Taly, Antoine; Lemoine, Damien; Martz, Adeline; Cunrath, Olivier; Grütter, Thomas

doi:10.1038/emboj.2012.75

Cited by 73 publications

(106 citation statements)

References 56 publications

(106 reference statements)

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“…For example, ATP binding to the cleft and subsequent cleft closure were predicted to occur based on proximity tethering (11), normal mode analysis (12), and both metal bridging and spectroscopic studies (13,14). In addition, the accessibility of both methanethiolsulfonate compounds and metals (Ag + and Cd 2+ ) to cysteine residues introduced into TM1 and TM2 (6)(7)(8) is consistent with the expansion of the external pore predicted from the zfP2X4 structures (Fig.…”

supporting

confidence: 58%

Inter- and intrasubunit interactions between transmembrane helices in the open state of P2X receptor channels

Heymann

Dai

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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P2X receptor channels open in response to the binding of extracellular ATP, a property that is essential for purinergic sensory signaling. Apo and ATP-bound X-ray structures of the detergentsolubilized zebrafish P2X4 receptor provide a blueprint for receptor mechanisms but unexpectedly showed large crevices between subunits within the transmembrane (TM) domain of the ATPbound structure. Here we investigate both intersubunit and intrasubunit interactions between TM helices of P2X receptors in membranes using both computational and functional approaches. Our results suggest that intersubunit crevices found in the TM domain of the ATP-bound crystal structure are not present in membraneembedded receptors but substantiate helix interactions within individual subunits and identify a hot spot at the internal end of the pore where both the gating and permeation properties of P2X receptors can be tuned. We propose a model for the structure of the open state that has stabilizing intersubunit interactions and that is compatible with available structural constraints from functional channels in membrane environments.pore-opening mechanism | transmembrane intersubunit crevices P 2X receptor channels are a family of trimeric cation-selective channels that are activated by extracellular ATP (1, 2). These ligand-gated ion channels are expressed in many tissues, including the central and peripheral nervous systems and the immune system, where they play a range of important roles in sensory signaling and inflammation (1, 3).Recent X-ray structures of the zebrafish P2X4 (zfP2X4) receptor in apo and ATP-bound forms (Protein Data Bank ID codes 4DW0 and 4DW1, respectively) have revealed the molecular design of these proteins (2, 4, 5) and have provided valuable information on how ATP binding triggers the opening of the transmembrane (TM) pore ( Fig. 1 A and B). ATP binds to a cleft between subunits within the large extracellular domain, inducing cleft closure and an accompanying lateral flexing of the β-sheet connecting the extracellular domain to the TM domain (5). The apo structure of the zfP2X4 receptor reveals that the TM1 helix is positioned peripheral to the TM2 helix and that the TM2 helix occludes the pore at the central axis within the outer half of the membrane (4, 5). In accord with this structure, accessibility studies show that the TM2 helix lines the aqueous pore and that the residues forming the gate are positioned within the occlusion in the apo structure (6-8). Lateral fenestrations within the extracellular domain provide a path for ions to enter and exit the extracellular vestibule positioned above this TM2 occlusion, and these fenestrations are thought to change conformation in response to ATP binding (9, 10). The ATP-bound structure shows that pore opening involves widening of the extracellular vestibule and an iris-like expansion of the pore (5). Intersubunit interactions within the TM domain in the apo structure are limited to the gate region of TM2 (5), and thus the pore expansion observed in the ATP-bound struc...

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supporting

confidence: 58%

Inter- and intrasubunit interactions between transmembrane helices in the open state of P2X receptor channels

Heymann

Dai

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…Those conformational changes are distinct from previously identified allosteric events essential for channel activations, such as the downward motion of cysteine-rich head domain, tightening of the ATP-binding site jaw and the upper vestibule expansions 5,6,8,9 . As revealed by the spontaneous closure of the ATP-binding site jaw (Fig.…”

Section: Discussionmentioning

confidence: 94%

“…1c and Supplementary Movie 1). Those structural changes are widely accepted to associate with channel opening [6][7][8]10 . Nevertheless, a comparison of pore size of the initial and representative conformation after MD simulations (Fig.…”

Section: Structural Dynamics Of Lf and Df Domains During Simulationsmentioning

confidence: 99%

“…To further confirm the crucial role of the relative motion of the LF and DF domains in channel activations, we introduced an engineered zinc bridge into the mutated P2X4 receptor containing histidine residues at those two positions. The zinc-bridge model of zfP2X4 V291H/T214H based on the closed crystal structure of zfP2X4 was constructed as previously described 8 (see Methods section). The distance (2.17 Å) and angle (107.7°) between the Zn 2 þ and coordinating atom NE2 of histidine residues (Fig.…”

Section: Structural Dynamics Of Lf and Df Domains During Simulationsmentioning

confidence: 99%

“…Numerous studies have demonstrated that a downward motion of the cysteine-rich head domain, tightening of the ATP-binding site jaw and upper vestibule expansion are essential for activation, desensitization and sustained activation of P2X receptors [5][6][7][8][9][10] , with data obtained from the application of multiple approaches, including electron microscopy 10 , voltage-clamp fluorometry 9 , engineering EC metal bridges 8,11 , normal mode analysis (NMA) 7 , molecular dynamics (MD) simulations 7 and fast-scanning atomic force microscopy 6 . Those studies provide new insights into the dynamics of EC domain as well as the movements of the whole receptor during channel gating.…”

mentioning

confidence: 99%

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Relative motions between left flipper and dorsal fin domains favour P2X4 receptor activation

Zhao¹,

Wang

Ma³

et al. 2014

Nat Commun

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Channel gating in response to extracellular ATP is a fundamental process for the physiological functions of P2X receptors. Here we identify coordinated allosteric changes in the left flipper (LF) and dorsal fin (DF) domains that couple ATP-binding to channel gating. Engineered disulphide crosslinking or zinc bridges between the LF and DF domains that constrain their relative motions significantly influence channel gating of P2X4 receptors, confirming the essential role of these allosteric changes. ATP-binding-induced alterations in interdomain hydrophobic interactions among I208, L217, V291 and the aliphatic chain of K193 correlate well with these coordinated relative movements. Mutations on those four residues lead to impaired or fully abolished channel activations of P2X4 receptors. Our data reveal that ATP-binding-induced altered interdomain hydrophobic interactions and the concomitant coordinated motions of LF and DF domains are allosteric events essential for the channel gating of P2X4 receptors.

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P2X Receptor Activation

Kawate

2017

Advances in Experimental Medicine and Biology

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Extracellular ATP-gated P2X receptors are trimeric non-selective cation channels important for many physiological events including immune response and neural transmission. These receptors belong to a unique class of ligand-gated ion channels composed of only six transmembrane helices and a relatively small extracellular domain that harbors three ATP-binding pockets. The crystal structures of P2X receptors, including the recent P2X3 structures representing three different stages of the gating cycle, have provided a compelling structural foundation for understanding how this class of ligand-gated ion channels function. These structures, in combination with numerous functional studies ranging from classic mutagenesis and electrophysiology to modern optogenetic pharmacology, have uncovered unique molecular mechanisms of P2X receptor function. This review article summarizes the current knowledge in P2X receptor activation, especially focusing on the mechanisms underlying ATP-binding, conformational changes in the extracellular domain, and channel gating and desensitization.

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Tightening of the ATP-binding sites induces the opening of P2X receptor channels

Cited by 73 publications

References 56 publications

Inter- and intrasubunit interactions between transmembrane helices in the open state of P2X receptor channels

Inter- and intrasubunit interactions between transmembrane helices in the open state of P2X receptor channels

Relative motions between left flipper and dorsal fin domains favour P2X4 receptor activation

P2X Receptor Activation

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