Identification and functional characterization a cysteine-rich peptide from the garlic (Allium sativum L.).

Due to the emergence of drug resistance of pathogens, it seem various strategies to be required to discover and develop new antimicrobial agents. Plant antimicrobial peptides (AMPs) can be promising alternative candidates against a variety of pathogens. Recently, various plant peptides have been identified and classified. Plant defensins are a class of cysteine-rich peptides with broad antimicrobial spectrum effects. In this study, an antimicrobial plant defensin peptide was identified successfully from EST library of garlic (Allium sativum L.) as well as expressed in E. coli expression system. The coding sequence of garlic defensin consist of an open reading frame (ORF) containing 216 base pairs that encodes a peptide of 71 amino acids with a putative extracellular signal peptide (24 amino acids) at the N- terminus. Analyze experimental data obtained from antimicrobial susceptibility assays shows that the garlic defensin has antibacterial effect against Escherichia coli and Staphylococcus aureus as models for Gram-negative and Gram positive bacteria, respectively. On the other hand, it was found that this defensin also possessed temperature and pH stability and its activity remained constant in different temperature and pH conditions. In summary, our findings provides important insights for producing and developing new potential antimicrobial compounds by using chemical synthesis and/or recombinant techniques in the future. [Display omitted] • Antimicrobial peptides represent a large family of small cysteine-rich cationic peptides. • Plant defensins play important roles in plant immune responses against pathogenic bacteria. • A plant defensin from garlic (Allium sativum L.) were identified using in silico and in vitro methods. • Some structural, physicochemical, and biological features of identified defensin were investigated and characterized. • This defensin appears can be considered as a potential peptide antibiotic drug for development and further assessment in the future. [ABSTRACT FROM AUTHOR]