Comparative study of pathogenesis-related protein 5 (PR5) of different Zingiberaceae species

Pathogenesis-related protein 5 (PR5) is a family of proteins that are induced by different phytopathogens in many plants and share significant sequence similarity with thaumatin. In the present study, 8 putative PR5 genes were cloned from different species of Zingiberaceae, viz., Alpinia luteocarpa, Curcuma amada, C. aromatica, C. longa, Elettaria cardamomum, Hedychium coronarium, Zingiber officinale and Z. zerumbet. Deduced sequences encode precursor proteins of 215 to 230 amino acid residues and share high homology with a number of other PR5 genes. The phylogenetic analysis of all the PR5s of Zingiberaceae species showed that all of them share significant evolutionary history. The secondary and 3-D structure comparison with 3 known PR5s (CaPR5, ZoPR5 & ZzPR5) revealed many striking similarities. In addition, we also generated models of their 3-D structure, the docking interactions between PR5 and the ligand beta-(1,4)-D-glucan, and the analysis of various protein properties, which has helped in determining the efficiency of PR5 proteins. These analyses further led to the identification of putative antimicrobial domains in these PR5s, which remain conserved.