1
|
Mohan MK, Abraham N, R P R, Jayaseelan BF, Ragnarsson L, Lewis RJ, Sarma SP. Structure and allosteric activity of a single-disulfide conopeptide from Conus zonatus at human α3β4 and α7 nicotinic acetylcholine receptors. J Biol Chem 2020; 295:7096-7112. [PMID: 32234761 DOI: 10.1074/jbc.ra119.012098] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 03/26/2020] [Indexed: 11/06/2022] Open
Abstract
Conopeptides are neurotoxic peptides in the venom of marine cone snails and have broad therapeutic potential for managing pain and other conditions. Here, we identified the single-disulfide peptides Czon1107 and Cca1669 from the venoms of Conus zonatus and Conus caracteristicus, respectively. We observed that Czon1107 strongly inhibits the human α3β4 (IC50 15.7 ± 3.0 μm) and α7 (IC50 77.1 ± 0.05 μm) nicotinic acetylcholine receptor (nAChR) subtypes, but the activity of Cca1669 remains to be identified. Czon1107 acted at a site distinct from the orthosteric receptor site. Solution NMR experiments revealed that Czon1107 exists in equilibrium between conformational states that are the result of a key Ser4-Pro5 cis-trans isomerization. Moreover, we found that the X-Pro amide bonds in the inter-cysteine loop are rigidly constrained to cis conformations. Structure-activity experiments of Czon1107 and its variants at positions P5 and P7 revealed that the conformation around the X-Pro bonds (cis-trans) plays an important role in receptor subtype selectivity. The cis conformation at the Cys6-Pro7 peptide bond was essential for α3β4 nAChR subtype allosteric selectivity. In summary, we have identified a unique single-disulfide conopeptide with a noncompetitive, potentially allosteric inhibitory mechanism at the nAChRs. The small size and rigidity of the Czon1107 peptide could provide a scaffold for rational drug design strategies for allosteric nAChR modulation. This new paradigm in the "conotoxinomic" structure-function space provides an impetus to screen venom from other Conus species for similar, short bioactive peptides that allosterically modulate ligand-gated receptor function.
Collapse
Affiliation(s)
- Madhan Kumar Mohan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| | - Nikita Abraham
- Institute for Molecular Bioscience, Queensland Bioscience Precinct, The University of Queensland, 306 Carmody Rd., St. Lucia Queensland 4072, Australia
| | - Rajesh R P
- Sathyabama Institute of Science and Technology, Jeppiaar Nagar, Rajiv Gandhi Salai, Chennai 600119, Tamil Nadu, India
| | | | - Lotten Ragnarsson
- Institute for Molecular Bioscience, Queensland Bioscience Precinct, The University of Queensland, 306 Carmody Rd., St. Lucia Queensland 4072, Australia
| | - Richard J Lewis
- Institute for Molecular Bioscience, Queensland Bioscience Precinct, The University of Queensland, 306 Carmody Rd., St. Lucia Queensland 4072, Australia
| | - Siddhartha P Sarma
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
| |
Collapse
|
2
|
Roy SW. Is Mutation Random or Targeted?: No Evidence for Hypermutability in Snail Toxin Genes. Mol Biol Evol 2016; 33:2642-7. [PMID: 27486220 DOI: 10.1093/molbev/msw140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ever since Luria and Delbruck, the notion that mutation is random with respect to fitness has been foundational to modern biology. However, various studies have claimed striking exceptions to this rule. One influential case involves toxin-encoding genes in snails of the genus Conus, termed conotoxins, a large gene family that undergoes rapid diversification of their protein-coding sequences by positive selection. Previous reconstructions of the sequence evolution of conotoxin genes claimed striking patterns: (1) elevated synonymous change, interpreted as being due to targeted "hypermutation" in this region; (2) elevated transversion-to-transition ratios, interpreted as reflective of the particular mechanism of hypermutation; and (3) much lower rates of synonymous change in the codons encoding several highly conserved cysteine residues, interpreted as strong position-specific codon bias. This work has spawned a variety of studies on the potential mechanisms of hypermutation and on causes for cysteine codon bias, and has inspired hypermutation hypotheses for various other fast-evolving genes. Here, I show that all three findings are likely to be artifacts of statistical reconstruction. First, by simulating nonsynonymous change I show that high rates of dN can lead to overestimation of dS. Second, I show that there is no evidence for any of these three patterns in comparisons of closely related conotoxin sequences, suggesting that the reported findings are due to breakdown of statistical methods at high levels of sequence divergence. The current findings suggest that mutation and codon bias in conotoxin genes may not be atypical, and that random mutation and selection can explain the evolution of even these exceptional loci.
Collapse
Affiliation(s)
- Scott W Roy
- Department of Biology, San Francisco State University
| |
Collapse
|
3
|
Gerdol M, Puillandre N, De Moro G, Guarnaccia C, Lucafò M, Benincasa M, Zlatev V, Manfrin C, Torboli V, Giulianini PG, Sava G, Venier P, Pallavicini A. Identification and Characterization of a Novel Family of Cysteine-Rich Peptides (MgCRP-I) from Mytilus galloprovincialis. Genome Biol Evol 2015. [PMID: 26201648 PMCID: PMC4558851 DOI: 10.1093/gbe/evv133] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We report the identification of a novel gene family (named MgCRP-I) encoding short secreted cysteine-rich peptides in the Mediterranean mussel Mytilus galloprovincialis. These peptides display a highly conserved pre-pro region and a hypervariable mature peptide comprising six invariant cysteine residues arranged in three intramolecular disulfide bridges. Although their cysteine pattern is similar to cysteines-rich neurotoxic peptides of distantly related protostomes such as cone snails and arachnids, the different organization of the disulfide bridges observed in synthetic peptides and phylogenetic analyses revealed MgCRP-I as a novel protein family. Genome- and transcriptome-wide searches for orthologous sequences in other bivalve species indicated the unique presence of this gene family in Mytilus spp. Like many antimicrobial peptides and neurotoxins, MgCRP-I peptides are produced as pre-propeptides, usually have a net positive charge and likely derive from similar evolutionary mechanisms, that is, gene duplication and positive selection within the mature peptide region; however, synthetic MgCRP-I peptides did not display significant toxicity in cultured mammalian cells, insecticidal, antimicrobial, or antifungal activities. The functional role of MgCRP-I peptides in mussel physiology still remains puzzling.
Collapse
Affiliation(s)
- Marco Gerdol
- Department of Life Sciences, University of Trieste, Italy
| | - Nicolas Puillandre
- Muséum National d'Histoire Naturelle, Département Systématique et Evolution, ISyEB Institut (UMR 7205 CNRS/UPMC/MNHN/EPHE), Paris, France
| | | | - Corrado Guarnaccia
- Protein Structure and Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | | | | | - Ventislav Zlatev
- Protein Structure and Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Chiara Manfrin
- Department of Life Sciences, University of Trieste, Italy
| | | | | | - Gianni Sava
- Department of Life Sciences, University of Trieste, Italy
| | - Paola Venier
- Department of Biology, University of Padova, Italy
| | | |
Collapse
|
4
|
Morales-González D, Flores-Martínez E, Zamora-Bustillos R, Rivera-Reyes R, Michel-Morfín JE, Landa-Jaime V, Falcón A, Aguilar MB. Diversity of A-conotoxins of three worm-hunting cone snails (Conus brunneus, Conus nux, and Conus princeps) from the Mexican Pacific coast. Peptides 2015; 68:25-32. [PMID: 25703301 DOI: 10.1016/j.peptides.2015.02.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/31/2015] [Accepted: 02/11/2015] [Indexed: 12/31/2022]
Abstract
Conus marine snails (∼500 species) are tropical predators that use venoms mainly to capture prey and defend themselves from predators. The principal components of these venoms are peptides that are known as "conotoxins" and generally comprise 7-40 amino acid residues, including 0-5 disulfide bridges and distinct posttranslational modifications. The most common molecular targets of conotoxins are voltage- and ligand-gated ion channels, G protein-coupled receptors, and neurotransmitter transporters, to which they bind, typically, with high affinity and specificity. Due to these properties, several conotoxins have become molecular probes, medicines, and leads for drug design. Conotoxins have been classified into genetic superfamilies based on the signal sequence of their precursors, and into pharmacological families according to their molecular targets. The objective of this work was to identify and analyze partial cDNAs encoding conotoxin precursors belonging to the A superfamily from Conus brunneus, Conus nux, and Conus princeps. These are vermivorous species of the Mexican Pacific coast from which only one A-conotoxin, and few O- and I2-conotoxins have been reported. Employing RT-PCR, we identified 30 distinct precursors that contain 13 different predicted mature toxins. With the exception of two groups of four highly similar peptides, these toxins are diverse at both the sequence and the physicochemical levels, and they belong to the 4/3, 4/4, 4/5, 4/6, and 4/7 structural subfamilies. These toxins are predicted to target diverse nicotinic acetylcholine receptor (nAChR) subtypes: nx1d, muscle; pi1a-pi1d, α3β2, α7, and/or α9α10; br1a, muscle, α3β4, and/or α4β2; and nx1a-nx1c/pi1g and pi1h, α3β2, α3β4, α9β10, and/or α7.
Collapse
Affiliation(s)
- Daniel Morales-González
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico; Maestría en Ciencias (Neurobiología), Universidad Nacional Autónoma de México, Mexico
| | - Ernesto Flores-Martínez
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico; Maestría en Ciencias (Neurobiología), Universidad Nacional Autónoma de México, Mexico
| | - Roberto Zamora-Bustillos
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico; Laboratorio de Genética Molecular, Instituto Tecnológico de Conkal, Conkal, Yucatán 97345, Mexico
| | - Reginaldo Rivera-Reyes
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico
| | - Jesús Emilio Michel-Morfín
- Departamento de Estudios para el Desarrollo Sustentable de Zonas Costeras, CUCSUR-Universidad de Guadalajara, Gómez Farías 82, San Patricio-Melaque, Jalisco 48980, Mexico
| | - Víctor Landa-Jaime
- Departamento de Estudios para el Desarrollo Sustentable de Zonas Costeras, CUCSUR-Universidad de Guadalajara, Gómez Farías 82, San Patricio-Melaque, Jalisco 48980, Mexico; Posgrado en Ciencias Biológicas y Agropecuarias, Universidad Autónoma de Nayarit, Mexico
| | - Andrés Falcón
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico
| | - Manuel B Aguilar
- Laboratorio de Neurofarmacología Marina, Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro 76230, Mexico.
| |
Collapse
|