Identification and functional characterization of a novel fungal immunomodulatory protein from Postia placenta

Area of Science:

• Mycology
• Immunology
• Biochemistry

Background:

• Fungal immunomodulatory proteins (FIPs) are bioactive compounds with diverse biological activities.
• Identification of FIPs has primarily focused on edible macro fungi.
• Exploring non-edible fungi offers potential for novel FIP discovery.

Purpose of the Study:

• To identify and characterize a novel fungal immunomodulatory protein (FIP) from the basidiomycete fungus Postia placenta.
• To investigate the biological activities of the recombinant FIP-ppl, including hemagglutination, immunomodulation, and antitumor effects.
• To establish an efficient method for the identification, production, and isolation of new FIPs.

Main Methods:

• Genome mining using known FIPs as probes to identify the FIP-ppl gene.
• Gene synthesis and expression in Escherichia coli to produce a glutathione S-transferase (GST) fusion protein.
• Purification of the recombinant protein (rFIP-ppl) using GST affinity chromatography and thrombin cleavage.
• Assays for hemagglutination, splenocyte proliferation, interleukin-2 release, and antitumor activity against human tumor cell lines.

Main Results:

• A novel FIP, FIP-ppl, was identified from Postia placenta, marking the first basidiomycete FIP outside edible macro fungi.
• Recombinant FIP-ppl exhibited hemagglutination activity against rabbit red blood cells.
• rFIP-ppl stimulated mouse splenocyte proliferation and enhanced interleukin-2 (IL-2) release.
• rFIP-ppl demonstrated significant inhibition of human tumor cell proliferation and induced apoptosis, with greater efficacy against gastric cancer cells (MGC823) than hepatoma cells (HepG2).

Conclusions:

• This study presents an effective strategy for discovering and producing novel FIPs from fungal genomes.
• FIP-ppl possesses immunomodulatory and antitumor properties, suggesting potential therapeutic applications.
• The findings open avenues for exploring non-edible fungi as sources of novel bioactive compounds for human health.