title: Molecular Characterization and In Silico Analysis of Defensin From Tor putitora (Hamilton).
abstract: Antimicrobial peptides (AMPs) are vital constituents of innate immune system. In fish, one of the most important AMP is β-defensin that has a potential to activate the adaptive immune system. β-defensin is a cysteine-arginine-rich cationic AMP with broad spectrum activity against microbes. In this study, we identified cloned and characterized β-defensin 1 from Tor putitora, a cold water fish species also known as mahseer. An open reading frame of β-defensin 1 was amplified, cloned and sequenced which encodes a peptide of 67 amino acid residues. The pro-peptide includes a signal peptide comprising 24 amino acids as predicted by Signal P along with a mature peptide of 43 amino acid residues. Tor putitora β-defensin 1 (TP-βdf1) has a molecular weight of 4.6 kDa with a pI of 8.35. Six cysteine residues are present in the mature peptide which is a characteristic feature of defensins. All six cysteine residues are involved in the formation of three intra-molecular disulfide bonds. Three-dimensional modeling of mature peptide of TP-βdf1 was carried out using Modeller 9.10, and validated TP-βdf1 model revealed three β-sheets. The cysteine residues form three disulfide bonds in the pattern of Cys(1)-Cys(5), Cys(2)-Cys(4), Cys(3)-Cys(6) stabilizing the β-sheet. Structural analysis revealed three β-strands and an α-helix at the N terminus. Phylogenetic analysis revealed that the β-defensin 1 of Tor putitora was close to Megalobrama amblycephala which possibly suggests that TP-βdf1 peptide sequence is quite similar to β-defensin peptide sequences of carps and minnows.
authors.affiliation: Directorate of Coldwater Fisheries Research, Bhimtal Nainital, Uttarakhand, 263136, India.
authors.forename: Preeti
authors.initials: P
authors.lastname: Chaturvedi
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Dhanik
authors.forename: Amit
authors.initials: A
authors.lastname: Pande
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003530:Cyprinidae / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D021382:Protein Sorting Signals; D017433:Protein Structure, Secondary; D023083:beta-Defensins / Q000235:genetics / Q000378:metabolism*
chemical_list: D004220:Disulfides; D021382:Protein Sorting Signals; D023083:beta-Defensins; D003545:Cysteine