Part:BBa_K2738006
Ovispirin fused to N-ter of Ferritin protein
Part: BBa_K2738006 (Ferritin-ovispirin)
Description
We aimed to fuse antimicrobial peptides to self-assembling multimeric proteins giving us star-shape antimicrobial peptides called StarCores. The StarCore described here is a result of the fusion of Ferritin (self-assembling protein) to ovispirin (antimicrobial peptide) via golden-gate assembly. The fusion protein expression is regulated by T7-promoter.
Ferritin is a universal intracellular protein produced by almost all living organisms, including algae, bacteria, higher plants, and animals. Ferritin is a globular protein complex consisting of 24 protein subunits forming a nanocage. Ovispirin is an alpha-helical antimicrobial peptide derived from derived SMAP29 peptide.It was found to inhibit several antibiotic-resistant bacterial strains.
Using homology modelling, we obtained the structure of ferritin-ovispirin fusion monomer protein. Using homology alignment, we were able to reconstruct the assembled ferritin-ovispirin monomer into the multimeric star-shaped construct.
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Monomer
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Assembly
Results:
Expression verification
The ferritin-ovispirin fusion protein was produced via cell-free expression system. The expression was verified by SDS gel as shown in the figure below.
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Figure 2. Cell free expression and purification of Ferritin-ovispirin-StarCore
2. MIC and growth curve We determined the MIC of ferritin-ovispirin StarCore to inhibit the growth of E coli and B subtilis (figure A and B). We performed growth curve assay for E coli and B subtilis with and without antimicrobial peptides as shown in figure C and D.
The results indicate that the ferritin-ovispirin StarCore has the MIC activity at 3 ug/ml for both E coli and B subtilis. Moreover, at 7.3 uM it also affects their growth kinetics to a significant extent indicating bactericidal activity. The antibacterial activity of ferritin-ovispirin StarCore is comparable to ovispirin at its MIC concentration (5 uM) alone as shown in the figure.
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3. Dynamic time-lapse imaging of bactericidal cell viability
The following results were obtained by time-lapse microscopy imaging, to study the bactericidal effect of antimicrobial peptides on B subtilis viability. Here we can observe that the presence of antimicrobial peptide proves to be toxic for the growing B subtilis which supports our growth curve data and MIC data.
Control:
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Ovispirin+Ferritin:
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4. Biocompatibility towards mammalian cell membrane
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Figure 1. Mammalian liposome leakage induced by ferritin-ovispirin StarCore (A) and the kinetics of liposome leakage (B). Ovispirin (5 uM) and ferritin-ovispirin (3 uM) are used at their MIC concentration obtained from previous results.
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To test the biocompatibility of the StarCores with mammalian membrane, we performed liposome leakage assay. Ovispirin alone lyses the liposome indicating damage to mammalian cell membrane. Ferritin-ovispirin has a reduced effect on the liposome leakage indicating an improvement in biocompatibility towards mammalian cell membrane. The Starcore ferritin-ovispirin has a safer profile in terms of membrane activity as compared to ovispirin alone at their respective MIC concentration.
References: Ovispirin obtained from DRAMP database: DRAMP03826 Ferritin obtained from RCSB. PDB number: 4XGS Star shaped antimicrobial peptides : 10.1038/NMICROBIOL.2016.162
Sequence and Features
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- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
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