Recombinant Ipomoea nil Antimicrobial protein PN-AMP1
Description
Mechanism of Action
Pn-AMP1 exhibits a dual mechanism:
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Membrane disruption: Accumulates at fungal hyphal septa, inducing ion leakage and cell lysis .
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Targeted binding: Interacts with sphingolipids (e.g., glucosylceramide) and chitin in fungal cell walls, inhibiting growth .
Key findings from mechanistic studies:
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Confocal microscopy revealed Pn-AMP1 localization in hyphal septa of Neurospora crassa and Saccharomyces cerevisiae, correlating with membrane integrity loss .
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Activity is pH-sensitive; antifungal effects diminish under acidic conditions (pH ≤ 2.0) .
Antifungal Activity
Pn-AMP1 shows broad-spectrum activity against chitin-containing fungi:
| Fungal Pathogen | IC₅₀ (μg/mL) | Reference |
|---|---|---|
| Neurospora crassa | 0.6–75 | |
| Candida albicans | 11–36 | |
| Phytophthora sojae | Significant inhibition in transgenic plants |
It also inhibits Gram-positive bacteria like Bacillus subtilis but shows minimal activity against Gram-negative species .
Transgenic Applications
Pn-AMP1 has been engineered into crops for disease resistance:
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Tomato and tobacco: Transgenic lines expressing Pn-AMP1 exhibited enhanced tolerance to fungal pathogens like Phytophthora sojae .
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Soybean: Overexpression of homologs (e.g., CaAMP1) reduced Phytophthora root rot severity by upregulating salicylic acid and jasmonic acid defense pathways .
Stability and Limitations
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Thermal stability: Retains activity at high temperatures due to disulfide bonds .
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pH sensitivity: Loses efficacy in acidic environments, limiting agricultural applications in low-pH soils .
Future Directions
Research priorities include optimizing recombinant production systems (e.g., E. coli or plant bioreactors) and improving pH stability through structural modifications. Field trials of Pn-AMP1-expressing crops are ongoing to validate long-term resistance and ecological impacts .
