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The Egh16-like virulence factor TrsA of the nematode-trapping fungus Arthrobotrys flagrans facilitates intrusion into its host Caenorhabditis elegans

Summary

Researchers discovered how a soil fungus that traps worms produces a special protein called TrsA to break down the worm’s protective outer layer. This protein acts like molecular scissors that weakens the worm’s skin and helps the fungus invade and spread throughout the worm’s body. The findings reveal a clever infection strategy used by predatory fungi and could help understand how similar fungi attack other organisms.

Background

Nematode-trapping fungi like Arthrobotrys flagrans form adhesive traps to capture and digest living nematodes such as Caenorhabditis elegans. The fungus must overcome the physical barrier of the nematode cuticle and epidermis to successfully colonize the host, but the molecular mechanisms involved in penetration remain poorly understood.

Objective

To characterize TrsA (trap-specific protein A), a virulence factor produced in adhesive traps and trophic hyphae of A. flagrans, and determine its role in facilitating nematode penetration and colonization.

Results

TrsA is upregulated during infection in traps and trophic hyphae and localizes to fungal-nematode contact sites. Deletion of trsA significantly increased time to nematode penetration. TrsA displays characteristics of lytic polysaccharide monooxygenases (LPMOs) with copper-dependent oxidase activity. Heterologous expression of trsA in C. elegans shortened lifespan and caused body softening and morphological defects.

Conclusion

TrsA represents a new family of LPMOs that likely targets oligosaccharides in the C. elegans cuticle and extracellular matrix, facilitating fungal entry and spreading. This work identifies a novel virulence mechanism in nematode-trapping fungi involving polysaccharide oxidation.
  • Published in:PLoS Pathogens,
  • Study Type:Experimental Research,
  • Source: PMID: 40853931, DOI: 10.1371/journal.ppat.1013370
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