Download MendeleyThe Tarantula Toxin omega-Avsp1a Specifically Inhibits Human Ca V 3.1 and Ca V 3.3 via the Extracellular S3-S4 Loop of the Domain 1 Voltage-Sensor.
Herzig, V., Chen, Y.C., Chin, Y.K., Dekan, Z., Chang, Y.W., Yu, H.M., Alewood, P.F., Chen, C.C., King, G.F.(2022) Biomedicines 10
- PubMed: 35625803
- DOI: https://doi.org/10.3390/biomedicines10051066
- Primary Citation of Related Structures:
7LVN - PubMed Abstract:
Inhibition of T-type calcium channels (Ca V 3) prevents development of diseases related to cardiovascular and nerve systems. Further, knockout animal studies have revealed that some diseases are mediated by specific subtypes of Ca V 3. However, subtype-specific Ca V 3 inhibitors for therapeutic purposes or for studying the physiological roles of Ca V 3 subtypes are missing. To bridge this gap, we employed our spider venom library and uncovered that Avicularia spec. ("Amazonas Purple", Peru) tarantula venom inhibited specific T-type Ca V channel subtypes. By using chromatographic and mass-spectrometric techniques, we isolated and sequenced the active toxin ω-Avsp1a, a C-terminally amidated 36 residue peptide with a molecular weight of 4224.91 Da, which comprised the major peak in the venom. Both native (4.1 μM) and synthetic ω-Avsp1a (10 μM) inhibited 90% of Ca V 3.1 and Ca V 3.3, but only 25% of Ca V 3.2 currents. In order to investigate the toxin binding site, we generated a range of chimeric channels from the less sensitive Ca V 3.2 and more sensitive Ca V 3.3. Our results suggest that domain-1 of Ca V 3.3 is important for the inhibitory effect of ω-Avsp1a on T-type calcium channels. Further studies revealed that a leucine of T-type calcium channels is crucial for the inhibitory effect of ω-Avsp1a.
Organizational Affiliation:
Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
