Macrobrachium rosenbergii cathepsin L: Molecular characterization and gene expression in response to viral and bacterial infections

Cathepsin L (MrCathL) was identified from a constructed cDNA library of freshwater prawn Macrobrachium rosenbergii. MrCathL full-length cDNA is 1161 base pairs (bp) with an ORF of 1026bp which encodes a polypeptide of 342 amino acid (aa) long. The eukaryotic cysteine proteases, histidine and asparagine active site residues were identified in the aa sequence of MrCathL at 143–154, 286–296 and 304–323, respectively. The pair wise clustalW analysis of MrCathL showed the highest similarity (97%) with the homologous cathepsin L from Macrobrachium nipponense and the lowest similarity (70%) from human. Phylogenetic analysis revealed two distinct clusters of the invertebrates and vertebrates cathepsin L in the phylogenetic tree. MrCathL and cathepsin L from M. nipponense were clustered together, formed a sister group to cathepsin L of Penaeus monodon, and finally clustered to Lepeophtheirus salmonis. High level of (P