Comparative Analysis of the Bacterial Membrane Disruption Effect of Two Natural Plant Antimicrobial Peptides.
In theMedicago truncatulagenome about 700 genes code for nodule-specific cysteine-rich (NCR) small peptides that are expressed in the symbiotic organ, the root nodule, where they control terminal differentiation of the endosymbiotic rhizobium bacteria to nitrogen-fixing bacteroids. Cationic NCR peptides were predicted to have antimicrobial activities. Here antibacterial activities of NCR247, NCR335, polymyxin B (PMB), and streptomycin were investigated and compared on two foodborne pathogensSalmonella entericaandListeria monocytogenesas representatives of Gram-negative and Gram-positive bacteria. The integrity of the bacterial membrane was seriously compromised by these NCR peptides. Different localization was observed for NCR247 and NCR335 in the treated bacteria, the peptides mostly accumulated in the cytosol inS. entericawhile they remained in the bacterial membrane inL. monocytogenes. Scanning electron microscopy revealed distinct membrane morphology of the peptide-treated bacteria. Complete cell disruption was induced by PMB and NCR335 inS. entericawhile NCR247 treatment resulted in extensive budding observed on the cell surface ofSalmonella. PMB had no effect onL. monocytogeneswhile NCR335 and NCR247 provoked morphological changes on this bacterium, the wholeListeriacell content was released in response to NCR335 treatment.
Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences Szeged, Hungary.
Attila
A
Farkas
Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences Szeged, Hungary.
Gergely
G
Maróti
Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences Szeged, Hungary.
Attila
A
Kereszt
Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences Szeged, Hungary.
Éva
É
Kondorosi
antimicrobial effect; foodborne pathogens; membrane disruption; nodule-specific cysteine-rich plant peptides (NCRs); peptide localization