Part:BBa_K5184033

HxTx-Hv1h

In order to eliminate spider mites, spider venom peptide HxTx-Hv1h is incorporated in our project to broaden the spectrum of molecular targets of venom peptides. HxTx-Hv1h is a small cysteine-rich venom peptide derived from Hadronyche versuta. Utilized as predatory toxin in nature, it carries the ability to cause paralysis and death in susceptible subjects by interfering with voltage-gated calcium and potassium channels. Given CaV and KV channels' roles in neurotransmitter release and neural impulse relay, HxTx-Hv1h serves as an effective pesticide.

Sequences

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]

Usage and Biology

HxTx-Hv1h is a 39aa long peptide containing 6 cysteine residues arranged to create a cysteine framework of C1xxxC2xxxC3C4xxxC5xxxC6, forming cysteine cross bridges between C1C4, C2C6, and between C3C5 [Fig1A].

Fig1: (A) Cysteine cross-bridge structure in HxTx-Hv1h (B) Secondary structure of HxTx-Hv1h, by structural prediction results from AlphaFold. The cysteine residues are colored orange, displaying their side chains and the rest of the peptide in white

Paralysis and mortal effects of susceptible subjects are achieved via HxTx-Hv1h inhibition on both CaV and KCa channels of susceptible targets by blocking the channels directly, resulting in impediment of fundamental nervous system responses in neuronal, muscular, and cardiac functions. (Specific site of inhibition depends on the concentration of neurotoxin).

Toxicity Verification

HxTx-Hv1h is synthesized using the vector pET28a-G1M5-His-SUMO-HxTx-Hv1h-GNA-His[Fig2B], of which is assembled using GoldenGate cloning and transformed into E. coli strain DH5ɑ. Colony PCR and sequencing is then carried out to verify the plasmid construct, of which is extracted and transformed into BL21(DE3) strain for expression. After IPTG induction and overnight incubation, the liquid culture is harvested and, after cell lysis, have an SDS-PAGE run. The results suggest that HxTx-Hv1h had achieved soluble expression. After several unsuccessful purification attempts, the supernatant is treated directly by SUMO protease [Fig2C].

Fig2: (A) G1M5 tag allows secretion of the fusion protein into extracellular milieu (B) Plasmid construct pET28a-G1M5-His-SUMO-HxTx-Hv1h-GNA-His (C) SDS-PAGE of supernatant and SUMO-treated supernatant, with supernatant of similarly treated supernatant of BL21(DE3) as control

The SUMO-digested supernatant's toxicity against T. urticae females is tested using a spraying method by Professor Huang from SCAU. Results from the toxicity assay suggests HxTx-Hv1h to be highly toxic against T. urticae, achieving an fatality of 90.91% within 72 hours.

Fig2: (A) T. urticae in their normal state, before being sprayed with treated supernatant (B) Dead T. urticae from spraying of treated supernatant (C) Survival plot of T. urticae being sprayed with supernatant containing HxTx-Hv1h over 72 hours, CK is similarly processed supernatant of BL21(DE3), acting as a control (D) Lethality data of T. urticae being sprayed with supernatant over 24, 48, and 72 hours, CK is the similarly processed supernatant of BL21(DE3), acting as a control

Part Collection

Our part collection provides a comprehensive list of venom peptides with a diverse range of molecular targets, which suppresses the development of drug resistance, and thus ensuring the efficacy of our acaricide. Through the incorporation of a G1M5-SUMO tag, all of the venom peptides are successfully expressed and digested by SUMO protease. According to the toxicity bioassay, all of the venom peptides display significant contact efficacy[Fig8A&B], especially PpVP2S, a novel MVP that we discovered by ourselves through genome mining. In future applications, we hope that our collection of venom peptides will not only be highly effective, but also solve the problem of drug resistance development that traditional pesticides always encounter.

Fig8: A. Survival plot of 6 venom peptides against female T. urticae using a spraying method, CK is induced liquid culture of BL21(DE3), of which acts as control D. Lethality data of 6 venom peptides over 24, 48, and 72 hours, CK is induced liquid culture of BL21(DE3), of which acts as control; data is the means of ± SD of three parallel replicate experiments

Our Part Collection

Current VP	Venom Name	Targeted Ion Channel	New?	Part Number	Original Specie
	PpVP2S	Ca	New	BBa_K5184043	Phytoseiulus persimilis
	PpVP1S	Ca	New	BBa_K5184042	Phytoseiulus persimilis
	PpVP1F	Ca	New	BBa_K5184038	Phytoseiulus persimilis
	rCtx4	Na		BBa_K5184021	Phoneutria depilata
	Cs1A	Ca		BBa_K5184032	Calommata signata
✳️	HxTx-Hv1h	Ca, K		BBa_K5184033	Hadronyche versuta