Multi-function Plant Defensin, Antimicrobial and Heavy Metal Adsorbent Peptide

Abstract

<strong>Background:</strong> Defensin peptide isolated from plants are often heterogeneous in length, sequence and structure, but they are mostly small, cationic and amphipathic. Plant defensins exhibit broad-spectrum antibacterial and antifungal activities against Gram-positive and Gram-negative bacteria, fungi and etc. Plant defensins also play an important role in innate immunity, such as heavy metal and some abiotic stresses tolerance.<br /> <strong>Objectives:</strong> In this paper, <em>in vitro</em> broad-spectrum activities, antimicrobial and heavy metal absorption, of a recombinant plant defensin were studied.<br /> <strong>Material and Methods:</strong> <em>SDmod</em> gene, a modified plant defensin gene, was cloned in pBISN1-IN (EU886197) plasmid, recombinant protein was produced by transient expression via Agroinfiltration method in common bean. The recombinant protein was tested for antibacterial activity against Gram-negative, Gram-positive bacteria and <em>Fusarium</em> sp. the effects of different treatments on heavy metal zinc absorption by this peptide were tested.<br /> <strong>Results: </strong>We confirmed the antibacterial activities of this peptide against Gram-negative (<em>Escherichia</em> <em>coli</em> and <em>Pseudomonas aeruginosa</em>) and Gram-positive (<em>Staphylococcus aureus </em>and <em>Bacillus cereus</em>) bacteria, and antifungal activities of this peptide against <em>Fusarium</em> spp. (<em>Fusarium oxysporu</em><em>m</em> and <em>Fusarium solani).</em> High metal absorption coefficient for this peptide was also observed.<br /> <strong>Results:</strong> Out of six actinobacterial isolates, VITVAMB 1 possessed the most efficient RO-16 decolorization property. It decolorized 85.6% of RO-16 (250 mg L^-1) within 24hrs. Isolate VITVAMB 1 was identified to be <em>Nocardiopsis </em>sp. Maximum dye decolorization occurred at pH 8, temperature 35^oC, 3% salt concentration and a dye concentration of 50 mg L^-1.<br /> <strong>Conclusions:</strong> Results suggesting that modified defensin peptide facilitates a broader range of defense activities. dedefensins are an important part of the innate immune system in eukaryotes. These molecules have multidimensional properties that making them promising agents for therapeutic drugs.