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¹ SRM University, Faculty of Science and Humanities, Department of Biotechnology, Division of Fisheries Biotechnology and Molecular Biology, Kattankulathur 603 203, Chennai, Tamil Nadu, India
² CSIR-Central Drug Research Institute, Lab PCN 206, Microbiology Division, B.S. 10/1, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow‐226031, Uttar Pradesh, India
³ The University of Texas at Austin, Institute for Cellular and Molecular Biology, 1 University Station A4800, Austin, Texas, 78712, USA
⁴ AIMST University, Faculty of Applied Sciences, Department of Biotechnology, Semeling, 08100 Bedong, Kedah, Malaysia DOI : 10.4194/1303-2712-v14_2_08 Viewed : 4697 - Downloaded : 3667 In this study, we have reported a full length cDNA of cathepsin B identified from the constructed cDNA library of snakehead murrel Channa striatus by genome sequence FLX technology. The identified full length C. striatus cathepsin B (CsCath B) is 1486 base pairs (bp) long which contains 990 bp open reading frame (ORF). The ORF region encodes 330 amino acids with a molecular mass of 36 k Da. This amino acid sequence contains three thiol protease motifs at 101-112, 275- 285 and 292-311 with their respective active sites viz., Cys¹⁰⁷, His²⁷⁷ and Asp²⁹⁷. CsCath B exhibited the maximum similarity (87%) with Cath B from mangrove red snapper, Lutjanus argentimaculatus. Phylogenetically, CsCath B is clustered together with the fish groups belonging to perciformes. A predicted 3D model of CsCath B revealed 11 α-helix and 10 β-strands. CsCath B contains higher percentage (10%) of coils due to the presence of many glycine residues (36 residues). The highest gene expression (P<0.05) was noticed in liver. Further, the expression was induced with fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila) infections. The predicted antimicrobial region of CsCath B was synthesized to study its antimicrobial property. The peptide exhibited the antimicrobial activity towards Gram negative and Gram positive bacteria. The overall results indicate that CsCath B is a potential molecule for further studies on murrel defense mechanism. Keywords : Cathepsin B, murrel, fungus, bacteria, antimicrobial peptide