The structure of a novel insecticidal neurotoxin, ω-atracotoxin-HV1, from the venom of an Australian funnel web spider

Abstract

A family of potent insecticidal toxins has recently been isolated from the venom of Australian funnel web spiders. Among these is the 37-residue peptide omega-atracotoxin-HV1 (omega-ACTX-HV1) from Hadronyche versuta. We have chemically synthesized and folded omega-ACTX-HV1, shown that it is neurotoxic, ascertained its disulphide bonding pattern, and determined its three-dimensional solution structure using NMR spectroscopy. The structure consists of a solvent-accessible beta-hairpin protruding from a disulphide-bonded globular core comprising four beta-turns. The three intramolecular disulphide bonds from a cystine knot motif similar to that seen in several other neurotoxic peptides. Despite limited sequence identity, omega-ACTX-HV1 displays significant structural homology with the omega-agatoxins and omega-conotoxins, both of which are vertebrate calcium channel antagonists; however, in contrast with these toxins, we show that omega-ACTX-HV1 inhibits insect, but not mammalian, voltage-gated calcium channel currents.

The dimerization and topological specificity functions of MinE reside in a structurally autonomous C‐terminal domain

“…An NMR sample was prepared by dissolving approximately 1.6 mg of the purified peptide in 260 l of 96% H 2 O/4% D 2 O in a susceptibility-matched microcell (Shigemi) and adjusting the pH to either 3.3 or 5.0; the final MinE 1-22 concentration was approximately 2.4 mM. Twodimensional TOCSY, DQF-COSY and NOESY spectra were collected at 279 K on a Bruker AMX 600 MHz spectrometer as described previously (Fletcher et al, 1997), with mixing times of 100 and 350 ms for the TOCSY and NOESY spectra respectively. Spectra were processed and analysed using XWINNMR (Bruker).…”

Optimising expression of the recombinant fusion protein biopesticide ω-hexatoxin-Hv1a/GNA inPichia pastoris:sequence modifications and a simple method for the generation of multi-copy strains

“…As shown in Table 1 levels of mortality observed for M. brassicae larvae injected with different doses of the original or modified fusion protein were highly similar verifying that mutagenesis of the Hv1a peptide had not disrupted or altered biological activity. Hv1a is a member of the -ACTX-1 family of 36-37 insecticidal residue peptides isolated from the Australian funnel web spider that block insect but not vertebrate, voltage-gated calcium channels ( [20] Fletcher et al, 1997). Previous alanine scanning mutagenesis studies by Tedford et al, [21] 2004 have identified 3 key functional residues (Pro10, Asn27, and Arg35) that determine specific binding to insect calcium channels.…”

Biological Activity of Insecticidal Toxins: Structural Basis, Site-Directed Mutagenesis and Perspectives

“…However, this analysis indicates that 1T0Z (from the Asian scorpion Buthus martensi Karsch) and 1I25 (from the Chinese bird spider O. huwena) may have anti-coleopteran properties due to the fact that they are in the same branch as 1WWN and 1TI5, respectively ( Figure 1). Studies have shown that insecticidal toxins purified from arthropod venoms exert their effects via specific interactions with ion channels and receptors in the central or peripheral nervous system (De Lima et al, 2007;Bloomquist, 2003;Johnson et al, 1998;Fletcher et al, 1997). B. martensi Karsch venom has four peptides related to the excitatory insect toxin family and 10 related to the depressant insect toxin (Goudet et al, 2002).…”