Synthetic Oligopeptides Mimicking γ-Core Regions of Cysteine-Rich Peptides of Solanum lycopersicum Possess Antimicrobial Activity against Human and Plant Pathogens

Abstract

Plant cysteine-rich peptides (CRPs) represent a diverse group of molecules involved in different aspects of plant physiology. Antimicrobial peptides, which directly suppress the growth of pathogens, are regarded as promising templates for the development of next-generation pharmaceuticals and ecologically friendly plant disease control agents. Their oligopeptide fragments are even more promising because of their low production costs. The goal of this work was to explore the antimicrobial activity of nine short peptides derived from the γ-core-containing regions of tomato CRPs against important plant and human pathogens. We discovered antimicrobial activity in peptides derived from the defensin-like peptides, snakins, and MEG, which demonstrates the direct involvement of these CRPs in defense reactions in tomato. The CRP-derived short peptides appeared particularly active against the gram-positive bacterium Clavibacter michiganensis, which causes bacterial wilt—opening up new possibilities for their use in agriculture to control this dangerous disease. Furthermore, high inhibitory potency of short oligopeptides was demonstrated against the yeast Cryptococcus neoformans, which causes serious diseases in humans, making these peptide molecules promising candidates for the development of next-generation pharmaceuticals. Studies of the mode of action of the two most active peptides indicate fungal membrane permeabilization as a mechanism of antimicrobial action.

The γ-Core Motif Peptides of AMPs from Grasses Display Inhibitory Activity against Human and Plant Pathogens

“…Structure–function studies of the classical defensins showed that the antimicrobial activity is associated, at least in part, with their γ-core motifs [ 17 , 30 ]. In our studies of tomato CRPs, we showed that the γ-core motifs of the CRPs belonging to other peptide families, such as snakins, MEG (Maternally Expressed Gene) peptides, and nsLTPs, also possess antimicrobial activity [ 18 ]. However, it remained unclear as to whether the γ-cores of the so-called 4-Cys DEFLs, knottin- and thionin-like peptides display antimicrobial properties.…”

“…The details of the production and storage of cultures of microorganisms used in this study are described at the VKM Home page [ 45 ]. Antimicrobial assays were accomplished according to the procedure described earlier [ 18 ]. In short, yeasts were grown on the YPD-P medium and the bacteria P. carotovorum and Cl.…”

“…In short, yeasts were grown on the YPD-P medium and the bacteria P. carotovorum and Cl. michiganensis were cultured on a modified YPD-P medium [ 18 ]. The Fusarium fungi were grown on potato dextrose agar at 25 °C for 7–8 days, and spores were washed off from the surface of the mycelia with sterile, distilled water.…”

“…Staining of yeast cells with propidium iodide in the presence of the γ-core peptides was carried out according to the protocol described earlier [ 18 ]. C. albicans or Cr.…”

“…γ-Core was defined as a region with a GXCX 3-9 C signature adopting a β-hairpin conformation in the AMP’s 3D structure [ 17 ]. In our previous work, we explored the antimicrobial activity of the γ-core motif peptides of a number of Solanum lycopersicum L. CRPs involved in response to infection with the fungus Fusarium oxysporum and the biogenic resistance inducers [ 18 ]. We showed that the γ-cores of several tomato CRPs possess potent antimicrobial activity against plant and human pathogens.…”