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Specific domains of plant defensins differentially disrupt colony initiation, cell fusion and calcium homeostasis in N eurospora crassa
Author(s) -
Muñoz Alberto,
Chu Meiling,
Marris Peter I.,
Sagaram Uma S.,
Kaur Jagdeep,
Shah Dilip M.,
Read Nick D.
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12634
Subject(s) - biology , neurospora crassa , defensin , biochemistry , microbiology and biotechnology , crassa , aequorin , intracellular , peptide , gene , mutant
Summary MsDef 1 and MtDef 4 from M edicago spp. are small cysteine‐rich defensins with potent antifungal activity against a broad range of filamentous fungi. Each defensin has a hallmark γ‐core motif ( GXCX 3–9 C ), which contains major determinants of its antifungal activity. In this study, the antifungal activities of MsDef 1, MtDef 4, and peptides derived from their γ‐core motifs, were characterized during colony initiation in the fungal model, N eurospora crassa . These defensins and their cognate peptides inhibited conidial germination and accompanying cell fusion with different potencies. The inhibitory effects of MsDef 1 were strongly mediated by the plasma membrane localized sphingolipid glucosylceramide. Cell fusion was selectively inhibited by the hexapeptide RGFRRR derived from the γ‐core motif of MtDef 4. Fluorescent labelling of this hexapeptide showed that it strongly bound to the germ tube plasma membrane/cell wall. Using N . crassa expressing the Ca 2+ reporter aequorin, MsDef 1, MtDef 4 and their cognate peptides were each shown to perturb Ca 2+ homeostasis in specific and distinct ways, and the disruptive effects of MsDef 1 on Ca 2+ were mediated by glucosylceramide. Together, our results demonstrate that MsDef 1 and MtDef 4 differ markedly in their antifungal properties and specific domains within their γ‐core motifs play important roles in their different modes of antifungal action.