Licosin, a multifunctional defensin peptide originated from the clinical fungus

Introduction: Defensins are small, cationic, cysteine-rich peptides that serve as key components of the innate immune system. Here, a new toxin-like fungal defensin named licosin was characterized from the clinical pathogen Methods: The analysis of its genomic and mRNA sequences revealed that the cDNA sequence of licosin was 207 bp without introns. The deduced precursor peptide of licosin contained 68 amino acids, composed of three parts: an N-terminal signal domain of 20 residues, a pro-peptide of 7 residues that ended at arginineserine, and a mature peptide of 41 residues at the C terminus. The amino acid sequence of mature licosin was further identified by LC-ESI-Q-TOF-MS/MS at the protein level. The mature licosin can form three intramolecular disulfide bonds. Circular dichroism spectrum analysis and 3D homology modeling revealed that mature licosin can form the representative cysteine-stabilized Results: Like most defensins, licosin exhibited good antimicrobial activities against gram-positive bacteria, including clinical isolates of MRSA and Discussion: These findings suggest that the active peptide secreted by clinical pathogenic fungi could be a treasure trove for the discovery of peptide-based drugs.