Recombinant Bacteriocin serracin-P 43 kDa subunit
Description
Structure and Sequence Analysis
The 43 kDa subunit of serracin-P is a critical component of a two-subunit bacteriocin complex (23 kDa and 43 kDa). Its N-terminal amino acid sequence (SEQ ID NO: 3) reveals 88% homology with the phage tail protein P2 of Salmonella enterica, suggesting a shared ancestry with temperate bacteriophages . Amino acid composition analysis indicates enrichment in lysine, arginine, aspartic acid, and leucine, aligning with structural motifs common in contractile phage tails .
| Amino Acid | Percentage Composition (%) |
|---|---|
| Lysine | 14.1 |
| Arginine | 12.3 |
| Aspartic Acid | 10.5 |
| Leucine | 9.8 |
Production and Purification
Production:
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Cultured in medium 863 (10 g/L bactopeptone, 10 g/L yeast extract, 10 g/L glucose, pH 7) .
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Induction with mitomycin C (0.7 mg/L) triggers bacteriocin synthesis via SOS system activation .
Purification:
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Ultrafiltration: 10,000 Da cutoff to concentrate HMW components .
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Mono Q HR 5/5 Anion Exchange: Eluted with 0–1 M NaCl gradient .
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Sephacryl S1000 Gel Filtration: Confirms a molecular weight of ~66 kDa (23 + 43 kDa subunits) .
Purification Yield:
| Step | Total Activity (AU) | Yield (%) | Specific Activity (AU/mg) | Purification Fold |
|---|---|---|---|---|
| Induced Supernatant | 4.6 × 10⁷ | 100.0 | 2.0 × 10⁵ | 1.0 |
| Mono Q HR 5/5 | 1.9 × 10⁷ | 41.9 | 1.3 × 10⁶ | 3.2 |
| Sephacryl S1000 | 9.7 × 10⁶ | 20.8 | 9.7 × 10⁶ | 48.5 |
Functional and Evolutionary Insights
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Antibacterial Activity: Exhibits specificity against Erwinia amylovora (fire blight pathogen) and Pseudomonas spp., with activity units (AU) quantified via lawn assays .
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Phage Tail Homology: Structural resemblance to phage tails includes a contractile sleeve and basal plate, enabling membrane penetration .
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Thermostability: Retains activity after 30 min at 50°C, unlike heat-labile phage proteins .
Agricultural Applications
Serracin-P formulations (e.g., 2100UA/mL) demonstrate efficacy in controlling Erwinia amylovora on pear flowers, with comparable or superior results to streptomycin . Adjuvants like Congo red and humectants enhance field stability .
