Scientists Use New Peptide against Microbes

Research and Innovations 24 January 2018
UTMN scientists, in cooperation with the State Research Institute of Highly Pure Biopreparations and a commercial partner from Saint Petersburg, have studied the effect of a new synthetic peptide on bacteria cells and proved its low toxicity and highly efficient antimicrobial properties, reported RIA news agency. The research results have been published in the Journal of Peptide Science

The global scientific community recognized the advantage of antimicrobial peptides over other antibiotics long ago. Peptides are short chains of amino acid monomers. Under certain conditions, peptides become lethal to the majority of bacterial species. 

UTMN scientists decided to use a modified antibacterial peptide for plant protection. 

“Phytopathogens have become resistant to many pesticides currently in use,” explained one of the research authors, researcher from the X-BIO Institute of Environmental and Agricultural Biology, Alexey Vasilchenko. “It is a serious challenge for modern agriculture. Besides, agrochemicals can be harmful for the environment and human health. One of the solutions for fighting phytopathogens is hidden inside living organisms themselves: evolution has given them the ability to protect themselves against microorganisms through various molecules with antimicrobial activity – peptides in particular”. 

There are two ways of using such agents to protect plants from phytopathogens. One of them is breeding transgenic species able to produce antimicrobial peptides themselves. For example, transgenic varieties of rice, corn and potato synthetizing antimicrobial peptides are already being successfully used in agriculture. 

The second way is using biopesticides – spraying preparations containing antimicrobial peptides directly onto plants. 

The scientists from Saint Petersburg took the natural peptide indolicidin, harvested from cattle neutrophils (blood cells that destroy bacteria and other parasites), and replaced the L-tryptophan amino acid in it with D-phenylalanine. 

This change makes the peptide less toxic and more resistant to destructive enzymes. In turn, adding unsaturated fatty acid makes the peptide molecule more bactericidal. The modified antimicrobial peptide has been named In-58. 

“Despite all the advantages of antimicrobial peptides, they are still rarely used in practice, both in medicine and agriculture. First, a high concentration is toxic for plant and animal cells. In addition, peptides become unstable in a protease environment, as proteases decompose peptide molecules. 
However, modern bioinformatics allow us to modify the structure of peptides to liquidate the disadvantages of the original molecules. For instance, replacing a peptide’s natural L-amino acids with D-amino acids decreases cytotoxicity and at the same time increases the molecule’s resistance to proteases,” said Alexey Vasilchenko. 

The first step towards using antimicrobial peptides in practice is conducting experiments in which a potential biopesticide is thoroughly studied in laboratory conditions. At this stage, researchers study its antimicrobial mechanisms and evaluate the phytopathogen’s resistance and sustainability under conditions imitating practical use. There are still two more vital stages to go: laboratory testing on plants and field testing. 

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