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Monday, 20 July 2015

A novel antifungal peptide from leaves of the weed Stellaria media L

Available online 18 July 2015

Highlights

A novel peptide named SmAMP3 was isolated from leaves of common chickweed (Stellaria media L.).
SmAMP3 belongs to the family of hevein-like AMPs carrying a conserved chitin-binding site.
The peptide exhibits potent antifungal activity against plant pathogens in the micromolar range.
This peptide is constitutively expressed in above-ground organs and seeds of S. media plants.

Abstract

A novel peptide named SmAMP3 was isolated from leaves of common chickweed (Stellaria media L.) by a combination of acidic extraction and a single-step reversed-phase HPLC and sequenced. The peptide is basic and cysteine-rich, consists of 35 amino acids, and contains three disulphide bridges. Homology search revealed that SmAMP3 belongs to the family of hevein-like antimicrobial peptides carrying a conserved chitin-binding site. Efficient binding of chitin by SmAMP3 was proved by in vitro assays. Molecular modeling confirmed conservation of the chitin-binding module in SmAMP3 locating the variable amino acid residues to the solvent-exposed loops of the molecule. The peptide exhibits potent antifungal activity against important plant pathogens in the micromolar range, although it is devoid of antibacterial activity at concentrations below 10 μM. As judged by chromatographic behavior and mass spectrometric data, the peptide is constitutively expressed in above-ground organs and seeds of S. mediaplants, thus representing an important player in the preformed branch of the plant immune system.

Keywords

  • hevein-like peptide; 
  • antifungal activity; 
  • Stellaria media; 
  • leaves; 
  • chitin binding

Corresponding author. Division of Molecular Neurobiology, Department of Neuroreceptors and Neuroregulators, Shemyakin & Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation. Tel.: +7 495 3364022; fax: +7 495 3307301.
1
These two authors contributed equally to this work.