Recombinant Uperoleia mjobergii Uperin-3.6
Description
Antifungal Performance
Uperin-3.6 and its engineered analogues exhibit broad-spectrum activity against Candida species:
| Organism | MIC (mg/L) - Native Uperin-3.6 | MIC (mg/L) - Lys-Substituted Analogues |
|---|---|---|
| C. albicans | 64–128 | 16–64 (Upn-Lys6) |
| C. krusei | 64–128 | 32–64 (Upn-Lys5) |
| C. parapsilosis | 64–128 | 64–128 |
Key findings:
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Lysine substitutions (e.g., Upn-Lys6) reduce MIC values by up to 8-fold, correlating with increased cationicity .
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Hybrid peptides (e.g., KU2/KU3) combining Uperin-3.6 fragments with other AMPs show superior activity (MIC: 8–16 mg/L) .
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Synergy with conventional antifungals (e.g., fluconazole) enhances efficacy .
Antibacterial Mechanisms
Uperin-3.6 disrupts microbial membranes via:
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Cross-α amyloid fibril formation: Observed in related uperins (e.g., Uperin 3.5), inducing membrane damage .
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Secondary structure switching: Transition between α-helical and β-sheet conformations in response to lipid environments .
Biofilm Eradication
Uperin-3.6 demonstrates dose-dependent biofilm inhibition:
| Peptide | BEC-2 (mg/L)* | Biofilm Reduction (%) |
|---|---|---|
| Native Uperin-3.6 | 192 | 60–70 |
| Upn-Lys6 | 96 | 80–90 |
| Hybrid KU4 | 96 | 85–95 |
*BEC-2: Minimum concentration reducing biofilm metabolic activity by 50% .
Cytotoxic Effects
Despite potent antimicrobial activity, Uperin-3.6 and analogues show cytotoxicity in human cells:
| Cell Line | IC₅₀ (mg/L) - Uperin-3.6 | IC₅₀ (mg/L) - Hybrid Peptides |
|---|---|---|
| VK2/E6E7 (vaginal) | 16–32 | 8–16 |
| Het-1A (esophageal) | 32–64 | 16–32 |
This toxicity limits therapeutic use but highlights potential for topical applications .
Research Significance
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Structural insights: The helical and amyloidogenic properties of uperins provide templates for designing synthetic AMPs .
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Clinical potential: Recombinant Uperin-3.6 derivatives could address drug-resistant fungal infections, though cytotoxicity remains a challenge .
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Evolutionary context: Cross-α amyloid fibrils in uperins suggest ancient antimicrobial defense mechanisms conserved across eukaryotes .
