Mechanistic diversification within the microbial NLP cytolysin family

• Applicants: Dr. Isabell Albert; Professor Dr. Thorsten Nürnberger
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 519620684

Necrosis and ethylene-inducing peptide 1-like proteins (NLP) constitute a superfamily of microbial proteins produced by plant pathogenic bacteria, fungi and oomycetes. Many NLPs are pore-forming toxins (PFTs). Plant host sensitivity to cytolytic NLPs (cNLPs) is determined by plasma membrane (PM)-resident glycosylinositol phosphorylceramide (GIPC) sphingolipids, which act as NLP toxin receptors. Both, cNLPs and many PFTs affecting animal host cells bind to glycosylated lipid receptors, but in contrast to the latter, mechanistic understanding of cNLP oligomerization, pre-pore assembly and membrane insertion is lacking. Here, we propose to analyze cNLP oligomeric complex formation and the abilities of these proteins to establish ion-conducting pores in plant plasma membranes. We further propose to address the question why various plant pathogenic microbes produce multiple cNLPs. This will be achieved by conducting comparative analyses of several cNLPs from the same plant pathogenic species. Assays to be conducted comprise quantification of cytotoxic activities in leaves and on plant PM vesicles, cNLP binding assays to plant protoplasts, to GIPC preparations prepared from various host plants and GIPC sugar head groups, and electrophysiological analyses to study biophysical and biochemical features of the cNLP pore. Such assays will reveal whether cNLPs from the same or from different microbes share the same or different biochemical features, whether individual cNLPs exhibit preferential binding to different GIPC sugar head groups and whether different cNLPs from the same pathogen form heteromeric pores.

• DFG Programme: Research Grants