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Discovery and biological characterization of conotoxins from the venom of Conus Brunneus in Drosophila Melanogaster

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Date Issued:
2014
Summary:
Cone snails are venomous marine predators whose venom is a complex mixture of modified peptides (conopeptides). Conopeptides have direct specificity towards voltage- and ligand-gated ion channels and G-protein coupled receptors. More specifically, alpha conotoxins target nicotinic acetylcholine receptors (nAChR) and are of great interest as probes for different nAChR subtypes involved in a broad range of neurological function. Typically, the amount of peptide provided directly from the cone snails (from either dissected or “milked” venom) is minimal, thus hindering the wide use of bioassay-guided approaches for compound discovery. Biochemical-based approaches for discovery by means of identification and characterization of venom components can be used due to their compatibility with the small quantities of cone snail venom available; however, no direct assessment of the bioactivity can be gleaned from these approaches. Therefore, newly discovered conotoxins must be acquired synthetically, which can be difficult due to their complicated folding motifs. The ability to test small quantities of peptide for bioactivity during the purification process can lead to the discovery of novel components using more direct approaches. Presented here is the description of use of an effective method of bioassay-guided fractionation for the discovery of novel alpha conotoxins as well as further biological characterization of other known alpha conotoxins. This method requires minimal amounts of sample and evaluates, via in vivo electrophysiological measurements, the effect of conotoxins on the functional outputs of a well-characterized neuronal circuit in Drosophila melanogaster known as the giant fiber system. Our approach uses reversed-phase HPLC fractions from venom dissected from the ducts of Conus brunneus in addition to synthetic alpha conotoxins. Fractions were individually tested for activity, re-fractionated, and re-tested to narrow down the compound responsible for activity. A novel alpha conotoxin, bru1b, was discovered via the aforementioned approach. It has been fully characterized in the giant fiber system through the use of mutant flies, as well as tested in Xenopus oocytes expressing nicotinic acetylcholine channels and against the acetylcholine binding protein. Other well-known alpha conotoxins have also been characterized in the giant fiber system.
Title: Discovery and biological characterization of conotoxins from the venom of Conus Brunneus in Drosophila Melanogaster.
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Name(s): Heghinian, Mari D., author
Mari, Frank, Thesis advisor
Florida Atlantic University, Degree grantor
Charles E. Schmidt College of Science
Department of Chemistry and Biochemistry
Type of Resource: text
Genre: Electronic Thesis Or Dissertation
Date Created: 2014
Date Issued: 2014
Publisher: Florida Atlantic University
Place of Publication: Boca Raton, Fla.
Physical Form: application/pdf
Extent: 123 p.
Language(s): English
Summary: Cone snails are venomous marine predators whose venom is a complex mixture of modified peptides (conopeptides). Conopeptides have direct specificity towards voltage- and ligand-gated ion channels and G-protein coupled receptors. More specifically, alpha conotoxins target nicotinic acetylcholine receptors (nAChR) and are of great interest as probes for different nAChR subtypes involved in a broad range of neurological function. Typically, the amount of peptide provided directly from the cone snails (from either dissected or “milked” venom) is minimal, thus hindering the wide use of bioassay-guided approaches for compound discovery. Biochemical-based approaches for discovery by means of identification and characterization of venom components can be used due to their compatibility with the small quantities of cone snail venom available; however, no direct assessment of the bioactivity can be gleaned from these approaches. Therefore, newly discovered conotoxins must be acquired synthetically, which can be difficult due to their complicated folding motifs. The ability to test small quantities of peptide for bioactivity during the purification process can lead to the discovery of novel components using more direct approaches. Presented here is the description of use of an effective method of bioassay-guided fractionation for the discovery of novel alpha conotoxins as well as further biological characterization of other known alpha conotoxins. This method requires minimal amounts of sample and evaluates, via in vivo electrophysiological measurements, the effect of conotoxins on the functional outputs of a well-characterized neuronal circuit in Drosophila melanogaster known as the giant fiber system. Our approach uses reversed-phase HPLC fractions from venom dissected from the ducts of Conus brunneus in addition to synthetic alpha conotoxins. Fractions were individually tested for activity, re-fractionated, and re-tested to narrow down the compound responsible for activity. A novel alpha conotoxin, bru1b, was discovered via the aforementioned approach. It has been fully characterized in the giant fiber system through the use of mutant flies, as well as tested in Xenopus oocytes expressing nicotinic acetylcholine channels and against the acetylcholine binding protein. Other well-known alpha conotoxins have also been characterized in the giant fiber system.
Identifier: FA00004122 (IID)
Degree granted: Dissertation (Ph.D.)--Florida Atlantic University, 2014.
Collection: FAU Electronic Theses and Dissertations Collection
Note(s): Includes bibliography.
Subject(s): Drosophila melanogaster
Gastropoda -- venom
Peptides -- Structure
Venom
Held by: Florida Atlantic University Libraries
Sublocation: Digital Library
Links: http://purl.flvc.org/fau/fd/FA00004122
Persistent Link to This Record: http://purl.flvc.org/fau/fd/FA00004122
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Host Institution: FAU
Is Part of Series: Florida Atlantic University Digital Library Collections.