Ostreolysin
Description
Mechanism of Action
Ostreolysin targets membrane microdomains through a multi-step process:
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Binding: Recognizes cholesterol-sphingomyelin or ceramide phosphoethanolamine (CPE) complexes in lipid rafts .
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Oligomerization: Forms 13-meric pores with PlyB, creating 4.9–8 nm hydrophilic channels .
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Cytolysis: Induces colloid-osmotic lysis via Ca²⁺ influx and membrane blebbing .
Key Functional Properties
Cellular Toxicity
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Hemolysis: Disrupts erythrocyte membranes at nanomolar concentrations .
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Smooth Muscle Cells: Increases intracellular Ca²⁺ (≥7 nM OlyA/0.78 nM PlyB), causing vasoconstriction .
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Cancer Cells:
In Vivo Effects
Lipid Raft Imaging
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Fluorescent OlyA-mCherry selectively labels cholesterol-sphingomyelin domains in living cells .
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Internalized via caveolin-1-positive vesicles, enabling real-time membrane trafficking studies .
Bioinsecticide Development
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OlyA6/PlyB complexes show potent activity against Diabrotica virgifera (western corn rootworm) .
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Mechanism: Midgut epithelial vacuolization and basal lamina delamination .
Therapeutic Potential
Product Specs
Ostreolysin, derived from the oyster mushroom (Pleurotus ostreatus), is a pore-forming protein that targets membranes containing cholesterol and sphingomyelin. Its affinity for cholesterol-rich regions, particularly liquid-ordered phases, contributes to its cytotoxic effect on Chinese hamster ovary cells, which are known to have detergent-resistant membranes rich in cholesterol.
Recombinant Pleurotus Ostreatus Ostreolysin, produced in E. coli, is a single-chain polypeptide lacking glycosylation. It comprises 137 amino acids and has a molecular weight of 15 kDa.
Purification of Ostreolysin is achieved using proprietary chromatographic methods.
The lyophilized Ostreolysin protein is prepared from a concentrated solution (1mg/ml) containing 0.02% NaHCO3.
For reconstitution, it is advised to dissolve the lyophilized Ostreolysin in sterile 0.4% NaHCO3 to a minimum concentration of 100 µg/ml. This solution can be further diluted in other aqueous solutions if required.
While the lyophilized Pleurotus Ostreatus Ostreolysin remains stable at room temperature for up to 3 weeks, it is recommended to store it in a desiccated state below -18°C. Following reconstitution, the protein should be stored at 4°C and used within 2-7 days. For long-term storage, adding a carrier protein like 0.1% HSA or BSA is advised.
Avoid freeze-thaw cycles.
The purity of Ostreolysin is greater than 98.0%, as determined by:
(a) Gel filtration analysis.
(b) SDS-PAGE analysis.
Ostreolysin exhibits potent anti-carcinogenic activity against a range of colon cancer cell lines.
Protein concentration is determined spectrophotometrically at 280 nm. An extinction coefficient of 2.64 is used for a 0.1% (1mg/ml) solution at pH 8.0. This value is obtained from the DNA-man computer analysis program.
The N-terminal amino sequence is Ala-Tyr-Ala-Gln-Trp-Val.
Product Science Overview
Ostreolysin, particularly its recombinant form (rOlyA), has been shown to interact with cytoskeletal proteins such as α/β-tubulin . This interaction is crucial for the protein’s ability to induce adipocyte-associated activity, which involves the formation of small lipid droplets and the expression of genes related to mitochondrial biosynthesis . The protein’s cell-internalization ability is essential for these biological activities, and specific point mutations at conserved tryptophan sites can impair its function .
Ostreolysin exhibits a strong affinity for membranes rich in cholesterol and sphingomyelin . This lipid-binding characteristic is critical for its role in membrane permeabilization. Studies have shown that Ostreolysin, in combination with other proteins such as pleurotolysin B (PlyB), can form oligomeric structures that permeabilize lipid membranes . These oligomers are essential for the protein’s ability to induce cytolytic activity, making it a valuable tool for studying membrane dynamics and cell biology.
The recombinant form of Ostreolysin (rOlyA) is produced using genetic engineering techniques. This involves cloning the gene encoding Ostreolysin into a suitable expression vector, which is then introduced into a host organism, such as Escherichia coli. The host organism expresses the protein, which can be purified and used for various experimental applications. Recombinant production allows for the generation of large quantities of Ostreolysin with consistent quality, facilitating detailed studies of its structure and function.
Ostreolysin’s unique properties make it a valuable tool for various applications. Its ability to bind to specific membrane lipids and induce cytolytic activity has potential uses in drug delivery, cancer therapy, and the study of membrane dynamics. Additionally, its interaction with cytoskeletal proteins and role in adipocyte differentiation provide insights into cellular processes and potential therapeutic targets for metabolic diseases.
In summary, Ostreolysin from Pleurotus ostreatus is a fascinating protein with significant potential in scientific research and biotechnology. Its recombinant form, rOlyA, offers a versatile tool for studying membrane interactions, cytoskeletal dynamics, and cellular differentiation.
