Title:
Identification and characterization of a peptide toxin inhibitor of ClC-2 chloride channels

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dc.contributor.advisor McCarty, Nael A.
dc.contributor.advisor Harvey, Stephen C.
dc.contributor.author Thompson, Christopher Hal en_US
dc.contributor.committeeMember Hartzell, Criss
dc.contributor.committeeMember Kubanek, Julia
dc.contributor.committeeMember Lee, Robert
dc.contributor.department Biology en_US
dc.date.accessioned 2009-01-22T15:49:36Z
dc.date.available 2009-01-22T15:49:36Z
dc.date.issued 2008-11-05 en_US
dc.description.abstract ClC proteins encompass a large protein family consisting of both voltage-dependent chloride channels and chloride/proton exchangers that are found in both eukaryotes and prokaryotes. These proteins mediate Cl- flux across the plasma membrane or intracellular membranes of many cell types including neurons, epithelial cells, and skeletal muscle in mammals. Mutations in genes encoding these channels also contribute to several human diseases. The mechanism of ion conduction through ClC proteins is becoming better defined, largely due to the availability of a crystal structure of a bacterial ClC transporter. Because crystal structures only capture a snapshot a protein in a single conformation, however, the large conformational changes associated with channel opening and closing have remained largely undefined. In the cation channel field, ion conduction and conformational changes that occur during channel gating have been studied using peptide toxin inhibitors isolated from animal venoms. However, only one peptide toxin inhibitor of a chloride channel of known molecular identity has ever been identified. Georgia anion toxin 1 (GaTx1), inhibits the CFTR chloride channel, which is unrelated to ClC proteins on the levels of both three dimensional structure and primary sequence. Here, we describe the characterization of the inhibitory activity of Leiurus quinquestriatus hebraeus scorpion venom against the ClC-2 chloride channel. We found that the venom from this scorpion contains a peptide component that is capable of inhibiting the ClC-2 chloride channel. This component was isolated using standard chromatography techniques, and found that the active component is a 3.2 kDa peptide composed of 29 amino acids. We showed that the active toxin, Georgia anion toxin 2 (GaTx2), interacts with ClC-2 with an affinity in the picomolar range, and appears to slow channel opening. Finally, GaTx2 is not capable of inhibiting other members of the ClC protein family, other major chloride channels, or voltage-gated potassium channels. This toxin will provide a new tool for structure/function studies of ClC-2, and will hopefully serve as only the first toxin inhibitor available for this protein family. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/26604
dc.publisher Georgia Institute of Technology en_US
dc.subject Venom en_US
dc.subject Toxin en_US
dc.subject Chloride en_US
dc.subject Ion channel en_US
dc.subject.lcsh Chloride channels
dc.subject.lcsh Peptides
dc.subject.lcsh Recombinant toxins
dc.title Identification and characterization of a peptide toxin inhibitor of ClC-2 chloride channels en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename College of Sciences
local.contributor.corporatename School of Biological Sciences
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
relation.isOrgUnitOfPublication c8b3bd08-9989-40d3-afe3-e0ad8d5c72b5
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