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Structural and Functional Analysis of Peptides Derived from KEX2-Processed Repeat Proteins in Agaricomycetes Using Reverse Genetics and Peptidomics

Summary

Scientists studied special proteins in mushrooms that get cut up into small functional peptides by fungal enzymes. They created a method to find and identify these peptides in mushroom fruiting bodies and growth materials. When they removed the enzymes that cut these proteins, the mushrooms had problems growing and forming fruiting bodies, suggesting these enzymes are important for normal development.

Background

KEX2-processed repeat proteins (KEPs) are a recently defined class of fungal precursor proteins containing multiple peptide cores flanked by KEX2 protease cleavage sites. Genome mining has revealed that KEPs are widespread in the fungal kingdom, but their functions remain largely unknown. This study presents the first in-depth structural and functional analysis of KEPs in a basidiomycete.

Objective

To identify and characterize KEP-encoding genes in Coprinopsis cinerea, establish a detection protocol for derived peptides, confirm their presence in agaricomycetes, and determine their biological functions through reverse genetics and peptidomics approaches.

Results

Multiple KEP-derived peptides were confirmed in C. cinerea and edible mushrooms (Lentinula edodes, Pleurotus ostreatus, P. eryngii). CRISPR knockout of kep genes showed no detectable phenotype under axenic conditions, but knockout of kex genes caused defects in mycelial growth and fruiting body formation, suggesting KEX proteases target multiple substrates beyond KEPs.

Conclusion

KEP-derived peptides are secreted ribosomally synthesized peptides widely distributed in agaricomycetes. While KEP-processing KEX proteases are essential for mycelial growth and fruiting body formation, the specific investigated KEP-derived peptides likely function in biotic interactions rather than axenic growth. The established detection protocol enables future discovery and characterization of KEP-derived peptides.
  • Published in:Microbiology Spectrum,
  • Study Type:Experimental Research Study,
  • Source: PMID: 36314921, DOI: 10.1128/spectrum.02021-22
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