Latest revision as of 13:34, 30 October 2016

Orally Active Insecticidal Peptide (OAIP)

Introduction:

Figure 1. Orally Active Insecticidal Peptide

By ligating the IPTG induced promoter T7 (BBa_ I712074), strong ribosome binding site (BBa_B0034), OAIP, linker, and the 6X His-Tag (BBa_ K1223006), we are able to express OAIP, the toxin by IPTG induction.
This year we create a revolutionary system that integrates biological pesticides, automatic detector, sprinkler, and IoT. We made a database that contains most of the spider toxins and selected the target toxins by programming. Orally Active Insecticidal Peptide is coded for the venom of a spider, Selenotypus plumipes. It is under the control of the strong T7 promoter. A 6X His-Tag is added for further protein purification.

Figure 2. Orally Active Insecticidal Peptide structure

Mechanism of OAIP

Orally Active Insecticidal Peptide has a structure called ICK(inhibitor cysteine knot). This kind of structure contains three disulfide bonds. With this structure OAIP can resist the high temperature, acid base solution and the digest juice of insect gut. OAIP can bind on the voltage-gated sodium channel in the insect’s nervous system, making it paralyze and die eventually.

Features of OAIP

1. Non-toxic

Orally Active Insecticidal Peptide is non-toxic to mammals and bees. Since the structure of the target ion channel is different, Orally Active Insecticidal Peptide does not harm mammals and bees. So it is safe to use it as a biological pesticide.^[1][2]

2. Biodegradable

The toxin is a peptide, so it must degrade over time. After degradation, the toxin will become nutrition inside the soil.

3. Species-specific

According to reference, Orally Active Insecticidal Peptide has specificity to Lepidopteran (moths), Coleopteran (beetles) and Isopteran (termite). So another insect such as bees will not be killed.

4. Eco-friendly

Compare with a chemical pesticide, Orally Active Insecticidal Peptide will not remain in soil and water so that it will not pollute the environment and won’t harm the ecosystem.

Together, using OAIP is totally an environmentally friendly way for solving harmful insect problems by using this ion channel inhibitor as a biological pesticide.

Target insect:

Figure 3. Target insects

Experiment

Cloning

After assembling the DNA sequences from the basic parts, we recombined toxin gene to pSB1C3 backbones and conducted a PCR experiment to check the size of each part. The DNA sequence length of these parts is around 100-150 bp. In this PCR experiment, the toxin product's size should be near at 350-450 bp.

Figure 4.OAIP
The DNA sequence length of OAIP is around 100-150 b.p. In this PCR experiment, the product’s size should be close to 350-450 b.p.

Application of the part

1. Expressing

We chose E.coli Rosetta gami strain, which can form the disulfide bonds in the cytoplasm to express the protein. To verify the E.coli express the OAIP with disulfide bonds, we treated the sample in two different ways. A means adding β-mercaptoethanol and sample buffer. β-mercaptoethanol can break the disulfide bonds of OAIP and make it a linear form.

The other one adding sample buffer is the native form of OAIP which maintains its structure. B is adding only sample buffer. The two samples are treated in boiling water for 15 mins. The SDS-PAGE shows that the native OAIP is smaller than linear one because the disulfide bonds in OAIP make the whole structure a globular shape.

2. Analysis

We do the Bradford analysis to get the protein concentration.

Figure 5. Protein electrophoresis of P_T7 + RBS + OAIP+linker+6X His-Tag (control: Without constructed plasmid)
We can see the band of OAIP at 5-6 kDa.
A: add β-mercaptoethanol and sample buffer
B: add sample buffer

Figure 6. Protein electrophoresis of P_T7 + RBS + OAIP+linker+Lectin+linker+6X His-Tag (control: Without constructed plasmid)
We can see the band of P_T7 + RBS + OAIP+linker+Lectin+linker+6X His-Tag at 17-18 kDa.
A: add β-mercaptoethanol and sample buffer
B: add sample buffer

3.Purification

We sonicated the bacteria and purified the protein by 6X His-Tag behind the peptide using Nickel resin column. Then we ran the SDS-PAGE to verify the purification and analyze the concentration of OAIP.

Figure 7. Protein electrophoresis of OAIP-6X His-Tag purification.
A is the sonication product.
B is the elution product of purification.

Figure 8. Protein electrophoresis of P_T7 + RBS + OAIP+linker+Lectin+linker+6X His-Tag purification.
A is the sonication product. B is the elution product of purification.

4.Modeling

ccording to reference, the energy of Ultraviolet will break the disulfide bonds and the toxicity is also decreased. To take the parameter into consideration for our automatic system, we modeled the degradation rate of the protein and modified the program in our device. Therefore, Pantide was tested under the ultraviolet light. The protein electrophoresis was shown below.

Figure 9. SDS-PAGE gel and the concentrations of UV radiolytic oxidation test to native Orally active insecticidal peptide (OAIP, 5.3 kDa). The samples are marked on the top of gel.

5. Device

We designed a device that contains detector, sprinkler, and integrated hardware with users by APP through IoT talk. We use an infrared detector to detect the number of the pest and predict what time to spray the farmland. Furthermore, other detectors like temperature, humidity, lamination, pressure of carbon dioxide and on also install in our device. At the same time, the APP would contact the users that all the information about the farmland and spray biological pesticides automatically. This device can make farmers control the farmland remotely.

Results

Pantide-expressed E. coli Rosetta gami strain and diluted it with the three concentration.We applied the sample onto the leaf disks and put five cutworms into the separate cabinets for feeding assays. The positive control in the experiment was to apply Bacillus thuringiensis, which is the most widely-used bioinsecticide. We preserved all the result of the remained leaves sealing with the glass paper and calculated the ratio of the remained area on the leaves. The collected data were analyzed by t – test. Here are the feeding assay results.

Figure 10. Above is leaves remaining area of Negative control ( DDwater ), Positive control ( Bacillus thuringiensis bacteria ), OAIP+linker+6X His-Tag, OAIP+linker+snowdrop-lectin+linker+6X His-Tag

Figure 11. Above are leaves with of Negative control ( DDwater ), Positive control ( Bacillus thuringiensis bacteria ), OAIP+linker+His-Tag

Reference

1. Margaret C. Hardy, Norelle L. Daly, Mehdi Mobli, Rodrigo A. V. Morales, Glenn F. King, “Isolation of an Orally Active Insecticidal Toxin from the Venom of an Australian Tarantula,” PLoS ONE, 2013, 8
2.Monique J. Windley, Volker Herzig, Slawomir A. Dziemborowicz, Margaret C. Hardy, Glenn F. King and Graham M. Nicholson, “Spider-Venom Peptide as Bioinsecticide,” Toxins Review, 2012, 4, pp. 191-227.

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]