Molecular scaffold of a new pokeweed antifungal peptide deduced by 1H nuclear magnetic resonance

• Published in: International journal of biological macromolecules 2001-12, Vol.29 (4), p.251-258
• Main Authors: Gao, Guang-Hua, Liu, Wei, Dai, Ji-Xun, Wang, Jin-Feng, Hu, Zhong, Zhang, Ying, Wang, Da-Cheng
• Format: Article
• Language: English
• Subjects: Amino Acid Motifs; Amino Acid Sequence; Antifungal Agents - chemistry; Antifungal peptide; Circular Dichroism; Cysteine pairing; Disulfides; Hydrogen-Ion Concentration; Knottin-like peptide; Magnetic Resonance Spectroscopy; Molecular Sequence Data; Peptides - chemistry; Phytolacca americana - chemistry; Protein Conformation; Protein Structure, Secondary; Secondary structure; Sequence Homology, Amino Acid
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/S0141-8130(01)00171-4

The antifungal peptide from seeds of Phytolacca Americana (Pokeweed), designated PAFP-S hereinafter, is a recently found cationic peptide which consists of 38 amino acid residues and exihibites a broad spectrum of antifungal activity, including inhibition of certain saprophytic fungi and some plant pathogens. The secondary structure and three cysteine pairings have been investigated by 1H NMR analysis. The results show that the molecular scaffold of PAFP-S features a triple-stranded antiparallel β-sheet knotted by a typical disulfide bridge motif, which characterizes the knottin fold. CD spectroscopy indicates a high stability of the molecule in solution. Therefore, PAFP-S should be a new member of the knottin structural family and the first antifungal peptide that adopts the knottin-like fold.