Dissertation/Thesis Abstract

Exploring Ion Channel Mechanisms: From Toxin-based Tools to Computational Methods
by Salari, Autoosa, Ph.D., University of Missouri - Columbia, 2016, 195; 11012942
Abstract (Summary)

Few gating-modifier toxins have been reported to target low-voltage-activated (LVA) calcium channels, and the structural basis of toxin sensitivity remains incompletely understood. Studies of voltage-gated potassium [63] channels have identified the S3b-S4 “paddle motif,” which moves at the protein-lipid interface to drive channel opening, as the target for these amphipathic neurotoxins. Voltage-gated calcium (Cav) channels contain four homologous voltage sensor domains, suggesting multiple toxin binding sites. We show here that the S3-S4 segments within Cav3.1 can be transplanted into Kv2.1 to examine their individual contributions to voltage sensing and pharmacology. With these results, we now have a more complete picture of the conserved nature of the paddle motif in all three major voltage-gated ion channel types (Kv, Nav, and Cav). When screened with tarantula toxins, the four paddle sequences display distinct toxin binding properties, demonstrating that gating-modifier toxins can bind to Cav channels in a domain specific fashion. Domain III was the most commonly and strongly targeted, and mutagenesis revealed an acidic residue that is important for toxin binding. We also measured the lipid partitioning strength of all toxins tested and observed a positive correlation with their inhibition of Cav3.1, suggesting a key role for membrane partitioning.

Indexing (document details)
Advisor: Milescu, Mirela
Commitee: Chandrasekhar, Anand, King, Gavin, Milesca, Mirela, Milescu, Lorin
School: University of Missouri - Columbia
Department: Biological Sciences
School Location: United States -- Missouri
Source: DAI-B 80/04(E), Dissertation Abstracts International
Subjects: Neurosciences, Biophysics
Keywords: Calcium channels, Ion channels, Kinetic mechanism, Thermosensors, Toxins
Publication Number: 11012942
ISBN: 978-0-438-66575-0
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