An allosteric link connecting the lipid-protein interface to the gating of the nicotinic acetylcholine receptor

Domville, Jaimee A.; Baenziger, John E.

doi:10.1038/s41598-018-22150-x

Cited by 22 publications

(30 citation statements)

References 56 publications

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“…R301, which has the largest effect on desensitization when mutated, is conserved among many mammalian pLGICs including GABA A R and nAchR isoforms, and R299 is adjacent to R301 at the bottom of TM4. Mutations in this region of TM4 have profound effects on pLGIC desensitization (Bouzat et al, 1998; Li et al, 1992; Domville and Baenziger, 2018; Lee et al, 1994). R117 and R123 are located at the extracellular end of TM4, and boundary POPG with headgroups that interact with these residues have acyl chains that make contacts with intrasubunit sites on both sides of TM4 (Figures 8B and 5B).…”

Section: Discussionmentioning

confidence: 99%

Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel

Tong

Petroff

Hsu

et al. 2019

eLife

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Pentameric ligand-gated ion channels (pLGICs) are essential determinants of synaptic transmission, and are modulated by specific lipids including anionic phospholipids. The exact modulatory effect of anionic phospholipids in pLGICs and the mechanism of this effect are not well understood. Using native mass spectrometry, coarse-grained molecular dynamics simulations and functional assays, we show that the anionic phospholipid, 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG), preferentially binds to and stabilizes the pLGIC, Erwinia ligand-gated ion channel (ELIC), and decreases ELIC desensitization. Mutations of five arginines located in the interfacial regions of the transmembrane domain (TMD) reduce POPG binding, and a subset of these mutations increase ELIC desensitization. In contrast, a mutation that decreases ELIC desensitization, increases POPG binding. The results support a mechanism by which POPG stabilizes the open state of ELIC relative to the desensitized state by direct binding at specific sites.

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Section: Discussionmentioning

confidence: 99%

Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel

Tong

Petroff

Hsu

et al. 2019

eLife

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“…A common transmembrane-binding region suggests that perturbation of the transmembrane domains is a critical structural feature needed to potentiate nAChR opening. It is known that nAChR function is very sensitive to conformational changes in the transmembrane domain M4, which directly connects to the C-tail (42,43). Subtle alterations in the tertiary structure of M4 could easily alter the conformation of the C-tail, thereby affecting nAChR function.…”

Section: Discussionmentioning

confidence: 99%

“…Subtle alterations in the tertiary structure of M4 could easily alter the conformation of the C-tail, thereby affecting nAChR function. It was shown that a single C418W mutation in M4 of ␣1 increased sensitivity to ACh by 16-fold (42). M4 is also believed to act as a "lipid sensor" in ␣1 (43).…”

Section: Discussionmentioning

confidence: 99%

Discovery of an intrasubunit nicotinic acetylcholine receptor–binding site for the positive allosteric modulator Br-PBTC

Norleans

Wang

Kuryatov

et al. 2019

Journal of Biological Chemistry

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Edited by Mike Shipston Nicotinic acetylcholine receptor (nAChR) ligands that lack agonist activity but enhance activation in the presence of an agonist are called positive allosteric modulators (PAMs). nAChR PAMs have therapeutic potential for the treatment of nicotine addiction and several neuropsychiatric disorders. PAMs need to be selectively targeted toward certain nAChR subtypes to tap this potential. We previously discovered a novel PAM, (R)-7-bromo-N-(piperidin-3-yl)benzo[b]thiophene-2-carboxamide (Br-PBTC), which selectively potentiates the opening of ␣4␤2*, ␣2␤2*, ␣2␤4*, and (␣4␤4) 2 ␣4 nAChRs and reactivates some of these subtypes when desensitized (* indicates the presence of other subunits). We located the Br-PBTC-binding site through mutagenesis and docking in ␣4. The amino acids Glu-282 and Phe-286 near the extracellular domain on the third transmembrane helix were found to be crucial for Br-PBTC's PAM effect. E282Q abolishes Br-PBTC potentiation. Using (␣4 E282Q ␤2) 2 ␣5 nAChRs, we discovered that the trifluoromethylated derivatives of Br-PBTC can potentiate channel opening of ␣5-containing nAChRs. Mutating Tyr-430 in the ␣5 M4 domain changed ␣5-selectivity among Br-PBTC derivatives. There are two kinds of ␣4 subunits in ␣4␤2 nAChRs. Primary ␣4 forms an agonist-binding site with another ␤2 subunit. Accessory ␣4 forms an agonist-binding site with another ␣4 subunit. The pharmacological effect of Br-PBTC depends both on its own and agonists' occupancy of primary and accessory ␣4 subunits. Br-PBTC reactivates desensitized (␣4␤2) 2 ␣4 nAChRs. Its full efficacy requires intact Br-PBTC sites in at least one accessory and one primary ␣4 subunit. PAM potency increases with higher occupancy of the agonist sites. Br-PBTC and its derivatives should prove useful as ␣ subunit-selective nAChR PAMs.

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“…Studies suggest that M4 interactions with M1 and M3 in some pLGICs are necessary to promote effective interactions between the M4 C-terminus and the Cys-loop, which are located at the interface of the ECD and the TMD, and are important in coupling agonist binding to channel opening [ 19 , 20 ]. It is also possible that there are more direct links, for example W418 in the nAChR M4 α-helix has recently been shown to interact directly with S226 on the adjacent M1 α-helix, stabilizing the open state [ 21 ]. Thus understanding the interactions made by aromatic residues is an important step in understanding the mechanism of activation of pLGICs.…”

Section: Introductionmentioning

confidence: 99%

The roles of aromatic residues in the glycine receptor transmembrane domain

Tang

Lummis

2018

BMC Neurosci

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BackgroundCys-loop receptors play important roles in fast neuronal signal transmission. Functional receptors are pentamers, with each subunit having an extracellular, transmembrane (TM) and intracellular domain. Each TM domain contains 4 α-helices (M1–M4) joined by loops of varying lengths. Many of the amino acid residues that constitute these α-helices are hydrophobic, and there has been particular interest in aromatic residues, especially those in M4, which have the potential to contribute to the assembly and function of the receptor via a range of interactions with nearby residues.ResultsHere we show that many aromatic residues in the M1, M3 and M4 α-helices of the glycine receptor are involved in the function of the receptor. The residues were explored by creating a range of mutant receptors, characterising them using two electrode voltage clamp in Xenopus oocytes, and interpreting changes in receptor parameters using currently available structural information on the open and closed states of the receptor. For 7 residues function was ablated with an Ala substitution: 3 Tyr residues at the extracellular end of M1, 2 Trp residues located towards the centers of M1 and M3, and a Phe and a Tyr residue in M4. For many of these an alternative aromatic residue restored wild-type-like function indicating the importance of the π ring. EC50s were increased with Ala substitution of 8 other aromatic residues, with those in M1 and M4 also having reduced currents, indicating a role in receptor assembly. The structure shows many potential interactions with nearby residues, especially between those that form the M1/M3/M4 interface, and we identify those that are supported by the functional data.ConclusionThe data reveal the importance and interactions of aromatic residues in the GlyR M1, M3 and M4 α-helices, many of which are essential for receptor function.Electronic supplementary materialThe online version of this article (10.1186/s12868-018-0454-8) contains supplementary material, which is available to authorized users.

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An allosteric link connecting the lipid-protein interface to the gating of the nicotinic acetylcholine receptor

Cited by 22 publications

References 56 publications

Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel

Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel

Discovery of an intrasubunit nicotinic acetylcholine receptor–binding site for the positive allosteric modulator Br-PBTC

The roles of aromatic residues in the glycine receptor transmembrane domain

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