Comparative proteomic analysis reveals intracellular targets for bacillomycin L to induce Rhizoctonia solani Kühn hyphal cell death

• We study mechanism of action of bacillomycin L using the proteomic technique.
• Bacillomycin L could disrupt the intracellular calcium homeostasis.
• We propose a hypothetical model of mechanism of action of bacillomycin L.
• We provide new insights into the mode of action of iturins or other lipopeptides.

Bacillomycin L, a natural iturinic lipopeptide produced by Bacillus amyloliquefaciens, is characterized by strong antifungal activity against a variety of agronomically important filamentous fungi including Rhizoctonia solani Kühn. To further understand its antifungal actions, proteomes were comparatively studied within R. solani hyphal cells treated with or without bacillomycin L. The results show that 39 proteins were alternatively expressed within cells in response to this lipopeptide, which are involved in stress response, carbohydrate, amino acid and nucleotide metabolism, cellular component organization, calcium homeostasis, protein degradation, RNA processing, gene transcription, and others, suggesting that, in addition to inducing cell membrane permeabilization, iturin exhibits antibiotic activities by targeting intracellular molecules. Based on these results, a model of action of bacillomycin L against R. solani hyphal cells was proposed. Our study provides new insight into the antibiotic mechanisms of iturins.