Eudicot plant-specific sphingolipids determine host selectivity of microbial NLP cytolysins

Abstract

Necrosis and ethylene-inducing peptide 1-like (NLP) proteins constitute a superfamily of proteins produced by plant pathogenic bacteria, fungi, and oomycetes. Many NLPs are cytotoxins that facilitate microbial infection of eudicot, but not of monocot plants. Here, we report glycosylinositol phosphorylceramide (GIPC) sphingolipids as NLP toxin receptors. Plant mutants with altered GIPC composition were more resistant to NLP toxins. Binding studies and x-ray crystallography showed that NLPs form complexes with terminal monomeric hexose moieties of GIPCs that result in conformational changes within the toxin. Insensitivity to NLP cytolysins of monocot plants may be explained by the length of the GIPC head group and the architecture of the NLP sugar-binding site. We unveil early steps in NLP cytolysin action that determine plant clade-specific toxin selectivity.

Comparing Arabidopsis receptor kinase and receptor protein‐mediated immune signaling reveals BIK1‐dependent differences

“…Arabidopsis LRR‐RP RLP23 recognizes an immunogenic peptide motif (nlp20) found within necrosis and ethylene‐inducing peptide 1 (NEP1)‐like proteins (NLP) (Albert et al ., ). NLPs are produced by numerous plant pathogenic bacteria, oomycetes and fungi (Ottmann et al ., ; Lenarčič et al ., ), which makes the nlp20 pattern unique by occurring in three different microbial lineages (Böhm et al ., ). Like FLS2, functionality of LRR‐RP/SOBIR1 complexes also involves ligand‐induced recruitment of BAK1 or related SERKs (Albert et al ., ; Postma et al ., ), but little information about the molecular architecture of such a tripartite complex is available.…”

Pattern recognition receptors confer plant salt tolerance via WRKY18/WRKY40 transcription factors

“…Shared use of common signaling components between PTI and salt tolerance extends beyond BAK1/BIK1-dependent PRR pathways. Glycosyl inositol phosphorylceramide sphingolipids provide Na + sensors to induce Ca 2+ influx for SOS signaling under salt stress (Jiang et al, 2019), and also perception sites for bacterial/fungal/oomycete Necrosis and ethylene-inducing peptide 1-like (NLP) proteins (Lenarčič et al, 2017). Salt tolerance is limited by the Catharanthus roseus RK FER (Feng et al, 2018;Zhao et al, 2018).…”

Disruption of Arabidopsis neutral ceramidases 1 and 2 results in specific sphingolipid imbalances triggering different phytohormone‐dependent plant cell death programmes

“…During the past decade, significant progress has been made in understanding the function of sphingolipids in plant growth and development. This includes new evidence of their roles in plant defence (König et al ., ; Bi et al ., ; Lenarčič et al ., ), stomatal closure (Guo et al ., ) and stress response (Zheng et al ., ). However, there is still a substantial gap in our knowledge on the connection between sphingolipid signalling, phytohormones and PCD (Berkey et al ., ).…”

“…In animals, furthermore, their structural role, sphingolipid metabolites regulate many cellular processes including autophagy or apoptosis (Young et al ., ). In plants, sphingolipids are important players in diverse signalling pathways related to development and responses to biotic and abiotic stresses (König et al ., ; Bi et al ., ; Lenarčič et al ., ; Ali et al ., ). Plant sphingolipids are classified into four major groups: LCB, Cer, glucosylceramide (GlcCer) and glycosyl inositol phosphorylceramide (GIPC) (Pata et al ., ).…”