In Silico Studies And Functional Characterization Of A Napin Protein From Seeds Of Brassica Juncea

Pathogenicity related proteins and peptides have been utilized as natural substitute to control phytopathogenic microbes and insects. A 15 kDa Napin protein from seeds of Brassica juncea was identified and characterized. SDS-PAGE separated native 15 kDa protein into two peptidic molecular masses of approximately 10 kDa and 5 kDa under reduced conditions. Ammonium sulfate precipitation (70%) followed by gel filtration chromatography provided a highly purified protein. A homology model of B. juncea Napin (BjN) was developed by using PDB ID: 1SM7 as the template structure. BjN predicted model showed conserved topology and disulfide bond patterns similar to rapeseed napin; which however, possessed a long hyper variable region between helices III and IV. An extra internal repeat of residues 77-87 has been predicted as unique segment of BjN predicted model. BjN exhibited inhibitory activity against growth of different pathogenic bacterial and fungal strains assessed by disc diffusion method. A 60 mu g/disc concentration of the purified protein exhibited strong antibacterial activity towards Xanthomonas oryzae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, P. syringae and Bacillus subtilis. Similarly, BjN (90 mu g/disc) significantly inhibited the mycelial growth of Aspergillus flavus and Fusarium oxysporum. BjN also showed good insecticidal potential against Sitophilus oryzae and Tribolium castaneum at a dose of 1.5 mg. The strong antimicrobial as well as insecticidal activity shown by the protein signified its potential as arsenal of antimicrobial and insecticidal agents. (C) 2019 Friends Science Publishers