The role of four small-secreted proteins as virulence factors in the interaction of the nematode-trapping fungus Arthrobotrys flagrans with Caenorhabditis elegans

• Applicant: Professor Dr. Reinhard Fischer
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 554600902

Nematode-trapping fungi like Arthrobotrys flagrans produce adhesive trapping networks upon starvation and in the presence of nematodes. Fungal and nematode-derived low-molecular weight compounds are crucial for the recognition process. After capture, the nematode is paralyzed while the fungus penetrates the cuticle and colonizes the nematode body. It emerges that small-secreted proteins are important at different steps of the infection process. NipA is required for effective penetration and CyrA for quick paralysis. In this proposal four new virulence proteins will be studied, PefA, PefB, HinA and EinA. They will be all characterized by expression analyses during the trapping and digestion process, by deletion and overexpression in A. flagrans and heterologous expression in C. elegans. Heterologous expression will be followed by RNAseq analyses to gain insights into the target process in C. elegans. Preliminary results suggest the splice machinery of C. elegans as one target of PefB. This will be further studied by protein-interaction studies of PefB with certain spliceosome proteins. Besides these characterizations, interacting proteins of EinA and PefA will be identified. Both proteins are nuclear proteins and should act on DNA. Neither of them has a DNA-binding or activation domain, suggesting interaction with other DNA-binding proteins. If fungal proteins target host processes, e.g. in the nucleus, the fungal protein needs to be secreted by the fungus, translocated into the host cell and enter the nucleus. Translocation and virulence protein delivery will be studied in targeted approaches. One possibility is also the presence of a targeting sequence in the virulence factor sequences. One aim of the proposal is to identify such a targeting signal.

• DFG Programme: Research Grants