7PX2 | pdb_00007px2

Conotoxin Mu8.1 from Conus mucronatus

• PDB DOI: https://doi.org/10.2210/pdb7PX2/pdb

• Classification: TOXIN
• Organism(s): Conus mucronatus
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2021-10-07 Released: 2022-11-16 
• Deposition Author(s): Mueller, E., Hackney, C., Ellgaard, L., Morth, J.P.
• Funding Organization(s): Novo Nordisk Foundation

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.12 Å
• R-Value Free: 
  0.234 (Depositor), 0.232 (DCC) 
• R-Value Work: 
  0.217 (Depositor), 0.211 (DCC) 
• R-Value Observed: 
  0.218 (Depositor) 

Starting Model: experimental

Literature

A previously unrecognized superfamily of macro-conotoxins includes an inhibitor of the sensory neuron calcium channel Cav2.3.

Hackney, C.M., Florez Salcedo, P., Mueller, E., Koch, T.L., Kjelgaard, L.D., Watkins, M., Zachariassen, L., Tuelund, P.S., McArthur, J.R., Adams, D.J., Kristensen, A.S., Olivera, B., Finol-Urdaneta, R.K., Safavi-Hemami, H., Morth, J.P., Ellgaard, L.

(2023) PLoS Biol 21: e3002217-e3002217

• PubMed: 37535677 
• DOI: https://doi.org/10.1371/journal.pbio.3002217
• Primary Citation Related Structures: 
  7PX1, 7PX2


• PubMed Abstract: 
  

  Animal venom peptides represent valuable compounds for biomedical exploration. The venoms of marine cone snails constitute a particularly rich source of peptide toxins, known as conotoxins. Here, we identify the sequence of an unusually large conotoxin, Mu8.1, which defines a new class of conotoxins evolutionarily related to the well-known con-ikot-ikots and 2 additional conotoxin classes not previously described. The crystal structure of recombinant Mu8.1 displays a saposin-like fold and shows structural similarity with con-ikot-ikot. Functional studies demonstrate that Mu8.1 curtails calcium influx in defined classes of murine somatosensory dorsal root ganglion (DRG) neurons. When tested on a variety of recombinantly expressed voltage-gated ion channels, Mu8.1 displayed the highest potency against the R-type (Cav2.3) calcium channel. Ca2+ signals from Mu8.1-sensitive DRG neurons were also inhibited by SNX-482, a known spider peptide modulator of Cav2.3 and voltage-gated K+ (Kv4) channels. Our findings highlight the potential of Mu8.1 as a molecular tool to identify and study neuronal subclasses expressing Cav2.3. Importantly, this multidisciplinary study showcases the potential of uncovering novel structures and bioactivities within the largely unexplored group of macro-conotoxins.

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Organizational Affiliation: 
• Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark.
Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah, United States of America.
Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark.
Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America.
Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America.
Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark.
Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia.
Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, Australia.

Biological Assembly 1  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors.

Biological Assembly Evidence: SAXS

Biological Assembly 2  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 2 assigned by authors.

Biological Assembly 3  

Global Symmetry: Cyclic - C2  (Explore in 3D)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 3 assigned by authors.

Macromolecule Content 

• Total Structure Weight: 62.65 kDa 
• Atom Count: 4,283 
• Modeled Residue Count: 508 
• Deposited Residue Count: 534 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Conotoxin Mu8.1	A, B, C, D, E, F	89	Conus mucronatus	Mutation(s): 0
UniProt
Find proteins for A0A9X9ZA00 (Conus mucronatus) Go to UniProtKB:  A0A9X9ZA00
Find proteins for P0DRC4 (Conus mucronatus) Explore P0DRC4  Go to UniProtKB:  P0DRC4

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
EPE	G [auth A], H [auth B], I [auth C], J [auth D], K [auth E], L [auth F]	4-(2-HYDROXYETHYL)-1-PIPERAZINE ETHANESULFONIC ACID C8 H18 N2 O4 S JKMHFZQWWAIEOD-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.12 Å
• R-Value Free:  0.234 (Depositor), 0.232 (DCC) 
• R-Value Work:  0.217 (Depositor), 0.211 (DCC) 
• R-Value Observed: 0.218 (Depositor) 

Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 68.84	α = 90
b = 88.45	β = 116.71
c = 69.31	γ = 90

Software Package:

Software Name	Purpose
PHENIX	refinement
PHENIX	refinement
xia2	data reduction
xia2	data scaling
PHASER	phasing

Structure Validation

Entry History 

& Funding Information

Deposition Data

• Released Date: 2022-11-16 
Deposition Author(s): Mueller, E., Hackney, C., Ellgaard, L., Morth, J.P.

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Funding Organization	Location	Grant Number
Novo Nordisk Foundation	Denmark	--

Revision History  

• Version 1.0: 2022-11-16
  Type: Initial release
  
• Version 1.1: 2023-08-16
  Changes: Data collection, Database references, Refinement description
• Version 1.2: 2024-01-31
  Changes: Refinement description
• Version 1.3: 2024-11-06
  Changes: Structure summary