The cystine knot is responsible for the exceptional stability of the insecticidal spider toxin ω-Hexatoxin-Hv1a

Herzig, Volker and King, Glenn F. (2015) The cystine knot is responsible for the exceptional stability of the insecticidal spider toxin ω-Hexatoxin-Hv1a. Toxins, 7 10: 4366-4380. doi:10.3390/toxins7104366


Author Herzig, Volker
King, Glenn F.
Title The cystine knot is responsible for the exceptional stability of the insecticidal spider toxin ω-Hexatoxin-Hv1a
Journal name Toxins   Check publisher's open access policy
ISSN 2072-6651
Publication date 2015-01-01
Year available 2015
Sub-type Article (original research)
DOI 10.3390/toxins7104366
Open Access Status DOI
Volume 7
Issue 10
Start page 4366
End page 4380
Total pages 15
Place of publication Basel, Switzerland
Publisher MDPI AG
Collection year 2016
Language eng
Formatted abstract
The inhibitor cystine knot (ICK) is an unusual three-disulfide architecture in which one of the disulfide bonds bisects a loop formed by the two other disulfide bridges and the intervening sections of the protein backbone. Peptides containing an ICK motif are frequently considered to have high levels of thermal, chemical and enzymatic stability due to cross-bracing provided by the disulfide bonds. Experimental studies supporting this contention are rare, in particular for spider-venom toxins, which represent the largest diversity of ICK peptides. We used ω-hexatoxin-Hv1a (Hv1a), an insecticidal toxin from the deadly Australian funnel-web spider, as a model system to examine the contribution of the cystine knot to the stability of ICK peptides. We show that Hv1a is highly stable when subjected to temperatures up to 75 °C, pH values as low as 1, and various organic solvents. Moreover, Hv1a was highly resistant to digestion by proteinase K and when incubated in insect hemolymph and human plasma. We demonstrate that the ICK motif is essential for the remarkable stability of Hv1a, with the peptide’s stability being dramatically reduced when the disulfide bonds are eliminated. Thus, this study demonstrates that the ICK motif significantly enhances the chemical and thermal stability of spider-venom peptides and provides them with a high level of protease resistance. This study also provides guidance to the conditions under which Hv1a could be stored and deployed as a bioinsecticide.
Keyword Inhibitor cystine knot
Insecticidal toxin
Physicochemical stability
Proteolytic degradation
Spider toxin
Thermal stability
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2016 Collection
Institute for Molecular Bioscience - Publications
 
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