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Published on: May 4, 2018
An antimicrobial peptide Ar-AMP from amaranth (Amaranthus retroflexus L.) seeds
Aleksey Lipkin1, Veronika Anisimova, Aleksandra Nikonorova
1Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow.
Abstract:
A 30-residue antimicrobial peptide Ar-AMP was isolated from the seeds of amaranth Amaranthus retroflexus L. essentially by a single step procedure using reversed-phase HPLC, and its in vitro biological activities were studied. The complete amino acid sequence of Ar-AMP was determined by Edman degradation in combination with mass spectrometric methods. In addition, the cDNA encoding Ar-AMP was obtained and sequenced. The cDNA encodes a precursor protein consisting of the N-terminal putative signal sequence of 25 amino acids, a mature peptide of 30 amino acids and a 34-residue long C-terminal region cleaved during post-translational processing. According to sequence similarity the Ar-AMP belongs to the hevein-like family of antimicrobial peptides with six cysteine residues. In spite of the fact that seeds were collected in 1967 and lost their germination capacity, Ar-AMP retained its biological activities. It effectively inhibited the growth of different fungi tested: Fusarium culmorium (Smith) Sacc., Helminthosporium sativum Pammel., King et Bakke, Alternaria consortiale Fr., and Botrytis cinerea Pers., caused morphological changes in Rhizoctonia solani Kühn at micromolar concentrations and protected barley seedlings from H. sativum infection.
Insights
A novel antimicrobial peptide, Ar-AMP, was isolated from amaranth seeds. This hevein-like peptide effectively inhibits fungal growth and protects plants from infection.
Area of Science:
- Plant biochemistry
- Antimicrobial peptides
- Molecular biology
Background:
- Amaranth seeds (Amaranthus retroflexus L.) contain bioactive compounds.
- Antimicrobial peptides (AMPs) are crucial in plant defense.
- Hevein-like peptides represent a class of AMPs with known antifungal properties.
Purpose of the Study:
- To isolate and characterize a novel antimicrobial peptide from amaranth seeds.
- To determine the amino acid sequence and cDNA encoding the peptide.
- To investigate the in vitro biological activities of the isolated peptide against fungal pathogens.
Main Methods:
- Single-step isolation using reversed-phase HPLC.
- Amino acid sequencing via Edman degradation and mass spectrometry.
- cDNA sequencing and analysis of the precursor protein structure.
Main Results:
- A 30-residue antimicrobial peptide, Ar-AMP, was successfully isolated.
- Ar-AMP belongs to the hevein-like family, characterized by six cysteine residues.
- The peptide demonstrated significant in vitro inhibition of Fusarium culmorium, Helminthosporium sativum, Alternaria consortiale, and Botrytis cinerea.
- Ar-AMP induced morphological changes in Rhizoctonia solani and protected barley seedlings from H. sativum infection, even from aged seeds.
Conclusions:
- Ar-AMP is a potent, stable antimicrobial peptide with broad-spectrum antifungal activity.
- The peptide's efficacy against plant pathogens highlights its potential as a biopesticide.
- The discovery of Ar-AMP expands the understanding of plant-derived antimicrobial compounds.
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