Recombinant Nicotiana tabacum Osmotin-like protein
Description
Expression Systems
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Baculovirus-Insect System: Full-length osmotin cDNA (GenBank Accession M29279.1) was expressed in Sf9 insect cells, yielding functional protein with a hexahistidine tag for purification .
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Bacterial Expression: E. coli-produced rOSM retained antifungal activity post-renaturation but required codon optimization for solubility .
Purification Protocols
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Chromatography: Acid treatment followed by ion-exchange and affinity chromatography achieves >95% purity .
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Yield: Up to 10–12% of total cellular protein under salt-stress conditions in native tobacco cells .
Biotic Stress Responses
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Antifungal Activity: Disrupts fungal membrane integrity by binding phosphomannoproteins on cell walls, effective against Candida albicans (MIC: 10–20 µg/mL) and foodborne pathogens .
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Antibacterial Action: Inhibits Salmonella and E. coli via membrane permeabilization .
Abiotic Stress Tolerance
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Osmoprotection: Enhances proline accumulation and scavenges reactive oxygen species (ROS) in transgenic plants under salinity (428 mM NaCl) or drought .
Mammalian Therapeutic Effects
In Plant Studies
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Transgenic Tobacco: rOSM-expressing plants showed 30% higher germination rates under 250 mM NaCl and 2-fold increased chlorophyll retention .
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Signal Transduction: Upregulates MAPK pathways (e.g., GhMPK2) to enhance stress-responsive gene expression .
Biomedical Applications
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Stability: Resists pepsin digestion and retains activity at 60°C for 1 hour, though peptide derivatives require stabilization for in vivo use .
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Allergenicity: Binds human IgE but can be engineered to reduce epitope reactivity .
Challenges and Future Directions
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Production Scalability: Low yields in bacterial systems necessitate optimization of codon usage or eukaryotic hosts .
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Therapeutic Delivery: Requires conjugation with stabilizing agents to prolong half-life in vivo .
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Agricultural Integration: Field trials needed to assess rOSM’s efficacy in crops under combined stress conditions .
