In vivo and in vitro testing of native α-conotoxins from the injected venom of Conus purpurascens

Hoggard, Mickelene; Rodriguez, Alena M.; Cano, Herminsul; Clark, E. P.; Tae, Han Shen; Adams, David J.; Godenschwege, Tanja A.; Marí, Frank

doi:10.1016/j.neuropharm.2017.09.020

Cited by 11 publications

(5 citation statements)

References 30 publications

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“…Furthermore, with many possible variations of amino acid residues apart from conserved cysteines, conotoxins vary greatly in their ability to target different neuronal/muscular acetylcholine receptors [23]. The most studied conotoxin subfamily is α-conotoxins, that are known to naturally and selectively bind at nAChR subtypes that modulate the cholinergic pathway [24], as mentioned previously. α-Conotoxins commonly contain fewer than 20 amino acid residues with a compact structure including 2 disulfide bridges [25].…”

Section: Introductionmentioning

confidence: 99%

Effects of C-Terminal Carboxylation on α-Conotoxin LsIA Interactions with Human α7 Nicotinic Acetylcholine Receptor: Molecular Simulation Studies

Wen¹,

Hung²

2019

Marine Drugs

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α-Conotoxins selectively bind to nicotinic acetylcholine receptors (nAChRs), which are therapeutic targets due to their important role in signaling transmission in excitable cells. A previous experimental study has demonstrated that carboxylation of the C-terminal of α-conotoxin LsIA reduces its potency to inhibit human α7 nAChR relative to naturally amidated LsIA. However, little is known about the contribution of conformational changes in the receptor and interactions, induced by C-terminal amidation/carboxylation of conotoxins, to selective binding to nAChRs, since most conotoxins and some disulfide-rich peptides from other conotoxin subfamilies possess a naturally amidated C-terminal. In this study, we employ homology modeling and molecular dynamics (MD) simulations to propose the determinants for differential interactions between amidated and carboxylated LsIAs with α7 nAChR. Our findings indicate an overall increased number of contacts favored by binding of amidated LsIA versus its carboxylated counterpart. Toxin-receptor pairwise interactions, which may play a role in enhancing the potency of the former, include ARG10-TRP77, LEU141 and CYS17-GLN79 via persistent hydrogen bonds and cation-π interactions, which are weakened in the carboxylated form due to a strong intramolecular salt-bridge formed by ARG10 and carboxylated C-terminus. The binding of amidated LsIA also induces enhanced movements in loop C and the juxtamembrane Cys-loop that are closely associated with receptor function. Additionally, the impacts of binding of LsIA on the overall structure and inter-subunit contacts were examined using inter-residue network analysis, suggesting a clockwise tilting of the α7 C and F loops upon binding to carboxylated LsIA, which is absent for amidated LsIA binding. The predicted molecular mechanism of LsIA binding to the α7 receptor may provide new insights into the important role of the C-terminal in the binding potency of conotoxins at neuronal nAChRs for pharmacological purposes.

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Section: Introductionmentioning

confidence: 99%

Effects of C-Terminal Carboxylation on α-Conotoxin LsIA Interactions with Human α7 Nicotinic Acetylcholine Receptor: Molecular Simulation Studies

Wen¹,

Hung²

2019

Marine Drugs

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“…Another two novel α4/4-peptides were isolated from the venom of C. purpurascens : α-conotoxin PIC and its [P7O]-modified form. They blocked rat muscle receptors and human neuronal α3β2 nAChR with moderate affinity (IC 50 ~1 µM) [ 138 ] ( Table 2 ).…”

Section: Marine Origin Peptides Targeting Nachrsmentioning

confidence: 99%

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

et al. 2022

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The purpose of our review is to briefly show what different compounds of marine origin, from low molecular weight ones to peptides and proteins, offer for understanding the structure and mechanism of action of nicotinic acetylcholine receptors (nAChRs) and for finding novel drugs to combat the diseases where nAChRs may be involved. The importance of the mentioned classes of ligands has changed with time; a protein from the marine snake venom was the first excellent tool to characterize the muscle-type nAChRs from the electric ray, while at present, muscle and α7 receptors are labeled with the radioactive or fluorescent derivatives prepared from α-bungarotoxin isolated from the many-banded krait. The most sophisticated instruments to distinguish muscle from neuronal nAChRs, and especially distinct subtypes within the latter, are α-conotoxins. Such information is crucial for fundamental studies on the nAChR revealing the properties of their orthosteric and allosteric binding sites and mechanisms of the channel opening and closure. Similar data are provided by low-molecular weight compounds of marine origin, but here the main purpose is drug design. In our review we tried to show what has been obtained in the last decade when the listed classes of compounds were used in the nAChR research, applying computer modeling, synthetic analogues and receptor mutants, X-ray and electron-microscopy analyses of complexes with the nAChRs, and their models which are acetylcholine-binding proteins and heterologously-expressed ligand-binding domains.

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“…The α1 plasmid was corrected to normal α1 by PCR. The expression of nAChR subunits in Xenopus oocyte and electrophysiological tests were performed as described previously [18,36,44]. Briefly, each oocyte was injected with 45-55 ng cRNA (1000 ng/µL) of α1, β1, δ, and ε at a ratio of 2:1:1:1.…”

Section: Oocyte Two-electrode Voltage Clampmentioning

confidence: 99%

“…In general, the 3/5 subfamily of α-conotoxins mainly target fish or mammalian neuromuscular nAChRs; typical toxin members include GI [16][17][18][19], MI [20,21], GII [22], GIA [22], SIA [23], SI [24,25], CnIA [26], CIA [27], CIB [27], and MilIA [28]. A number of other conotoxins have also been found to act on neuromuscular nAChRs, such as EI [29], PIVA [30], OIVA [31], OIVB [32], PIB [33], EIVA [34], EIIA [35], PIC [36], and MIIIJ [37]. On the other hand, 4/3, 4/4, 4/5, 4/6, and 4/7 α-conotoxins usually target neuronal nAChRs [11,13].…”

Section: Introductionmentioning

confidence: 99%

The 3/4- and 3/6-Subfamily Variants of α-Conotoxins GI and MI Exhibit Potent Inhibitory Activity against Muscular Nicotinic Acetylcholine Receptors

Huang²,

Yu³

et al. 2021

Marine Drugs

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α-Conotoxins GI and MI belong to the 3/5 subfamily of α-conotoxins and potently inhibit muscular nicotinic acetylcholine receptors (nAChRs). To date, no 3/4- or 3/6-subfamily α-conotoxins have been reported to inhibit muscular nAChRs. In the present study, a series of new 3/4-, 3/6-, and 3/7-subfamily GI and MI variants were synthesized and functionally characterized by modifications of loop2. The results show that the 3/4-subfamily GI variant GI[∆8G]-II and the 3/6-subfamily variants GI[+13A], GI[+13R], and GI[+13K] displayed potent inhibition of muscular nAChRs expressed in Xenopus oocytes, with an IC50 of 45.4–73.4 nM, similar to or slightly lower than that of wild-type GI (42.0 nM). The toxicity of these GI variants in mice appeared to be about a half to a quarter of that of wild-type GI. At the same time, the 3/7-subfamily GI variants showed significantly lower in vitro potency and toxicity. On the other hand, similar to the 3/6-subfamily GI variants, the 3/6-subfamily MI variants MI[+14R] and MI[+14K] were also active after the addition of a basic amino acid, Arg or Lys, in loop2, but the activity was not maintained for the 3/4-subfamily MI variant MI [∆9G]. Interestingly, the disulfide bond connectivity “C1–C4, C2–C3” in the 3/4-subfamily variant GI[∆8G]-II was significantly more potent than the “C1–C3, C2–C4” connectivity found in wild-type GI and MI, suggesting that disulfide bond connectivity is easily affected in the rigid 3/4-subfamily α-conotoxins and that the disulfide bonds significantly impact the variants’ function. This work is the first to demonstrate that 3/4- and 3/6-subfamily α-conotoxins potently inhibit muscular nAChRs, expanding our knowledge of α-conotoxins and providing new motifs for their further modifications.

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In vivo and in vitro testing of native α-conotoxins from the injected venom of Conus purpurascens

Cited by 11 publications

References 30 publications

Effects of C-Terminal Carboxylation on α-Conotoxin LsIA Interactions with Human α7 Nicotinic Acetylcholine Receptor: Molecular Simulation Studies

Effects of C-Terminal Carboxylation on α-Conotoxin LsIA Interactions with Human α7 Nicotinic Acetylcholine Receptor: Molecular Simulation Studies

Marine Origin Ligands of Nicotinic Receptors: Low Molecular Compounds, Peptides and Proteins for Fundamental Research and Practical Applications

The 3/4- and 3/6-Subfamily Variants of α-Conotoxins GI and MI Exhibit Potent Inhibitory Activity against Muscular Nicotinic Acetylcholine Receptors

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