Difference between revisions of "Part:BBa K2278022"
(→Introduction) |
|||
| Line 30: | Line 30: | ||
<br> | <br> | ||
<b>Analysis of the restriction map </b> | <b>Analysis of the restriction map </b> | ||
| − | <figure><p style="text-align:center;"><img src="https://static.igem.org/mediawiki/parts/ | + | <figure><p style="text-align:center;"><img src="https://static.igem.org/mediawiki/parts/d/d3/LeucroI-gel2.png" width = "400"/><figcaption> Figure 1: <b>Analysis of the restriction map BBa_K2278022. </b> Digested fragments (Xba1 and Pst1) are electrophoresed through a 0.7% agarose gel. Control vector pSB1C3 contained an insert and expected size were 2034 and 700 bp (digestion was not total, hence the 2734 bp fragment). The fragment lengths of the tested clone were 2035 bp and 319 bp for the required insert.</figcaption></figure> |
<br> | <br> | ||
<p><b>Sequencing </p></b> | <p><b>Sequencing </p></b> | ||
| Line 42: | Line 42: | ||
The plasmid was then linearized and transferred in <i>Pichia pastoris</i> by electroporation. The integration is predicted to be at the pGAP location. Indeed, the pGAP promoter makes genome recombination easier in <i>Pichia pastoris</i>. | The plasmid was then linearized and transferred in <i>Pichia pastoris</i> by electroporation. The integration is predicted to be at the pGAP location. Indeed, the pGAP promoter makes genome recombination easier in <i>Pichia pastoris</i>. | ||
| − | <figure><p style="text-align:center;"><img src="https://static.igem.org/mediawiki/parts/ | + | <figure><p style="text-align:center;"><img src="https://static.igem.org/mediawiki/parts/0/00/LeucrocinI_gel2.png"/><figcaption> Figure 3 : <b>Integration of pGAP+BBa_K2278022 in <i>Pichia pastoris</i> </b> To verify the correct integration, we performed colony PCR and electrophoresed the product through a 0.7% agarose gel. A 824 bp fragment is expected if the integration is correct. |
</figcaption></figure> | </figcaption></figure> | ||
| − | Correct amplifications were observed for the | + | Correct amplifications were observed for the 3 colonies tested. Negative control with pPICZalpha presented no band, as expected. |
<br><br> | <br><br> | ||
Revision as of 13:58, 19 October 2017
Lecrocin I antimicrobial peptide with Alpha-Factor Secretion Signal Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21INCOMPATIBLE WITH RFC[21]Illegal XhoI site found at 244
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
Introduction
This DNA biobrick was designed in order to produce Leucrocin I antimicrobial peptide.
1- Biological background
Antimicrobial peptides (AMP) are phylogenetically ancient components of the innate defense of both invertebrates and vertebrates. In the context of growing bacterial antibiotic-resistance, these AMP are considered as potential new therapeutical candidates.Leucrocin I from Siamese crocodile white blood cells shows a good antibacterial activity towards Vibrio cholerae. Leucrocin I action has been observed with fluorescence and electron microscopy. The molecule is cationic and can target bacterial membranes. It creates pores in these membranes leading to the cell lysis. The peptide is a 7 amino acid residue : NGVQPKY with a molecular mass around 806.99 Da.
2- Usage in iGEM projects
The part was designed during the Croc’n Cholera project (team INSA-UPS-France 2017). It produces the leucrocin I AMP when associated with a yeast promoter. The α-factor (BBa_K1800001) sequence contains a RBS and a signal sequence to secrete the produced peptides.Experiments
1- Molecular biology
The gene was placed under the control of an alpha factor signal. IDT performed the DNA synthesis and delivered the part as gBlock. The construct was cloned by conventional ligation into the pSB1C3 plasmid. The construction was then inserted on plasmid pPICZa and integrated in the yeast genome.
Analysis of the restriction map
Sequencing
< img src="https://static.igem.org/mediawiki/parts/X/XX/XXXX.png" width = "700"/>
2- Integration in Pichia pastoris
The biobrick was placed under the control of the constitutive pGAP promoter (BBa_K431009) and was cloned in the pPICZalpha vector, an expression vector for the yeast Pichia pastoris. The plasmid was then linearized and transferred in Pichia pastoris by electroporation. The integration is predicted to be at the pGAP location. Indeed, the pGAP promoter makes genome recombination easier in Pichia pastoris.
Characterization
2. Toxicity assay
Leucrocin production was performed with Pichia pastoris in YPD 40 g/L glucose grown for 4 days at 30 °C with shacking. Supernatants from yeasts with or without the leucrocin encoding gene were sampled. The supernatants were used in a halo assay against V. harveyi as the target of Leucrocin. Briefly, 35mL of supernatants were freeze-dried and then resuspended in 3.5mL of water. A paper cut was soaked with one of these solutions and placed on a Petri plate inoculated with V. harveyi (figure 3).
Conclusion :
No inhibition halo was observed around the yeast patch. The Leucrocin I cytoxicity can not be demonstrated.Perspectives:
Higher concentration of yeast supernatants could be tried.Design Notes
A pGAP promoter is present on the pSB1C3 vector before the construction. It makes genome recombination easier in Pichia pastoris genome.
Part:BBa_K1800001: Alpha-Factor Secretion Signal
Source
The peptides DNA sequence has been obtained by reverse translate the amino acid sequence of the Leucrocin I proposed by Pata et al., 2011. Pata et al., 2011 had determinated the amino acid sequence by mass spectrometry analysis.