In silico prediction of active site and in vitro DNase and RNase activities of Helicoverpa-inducible pathogenesis related-4 protein from Cicer arietinum

Abstract

Plants are endowed with an innate immune system, which enables them to protect themselves from pest and pathogen. The participation of pathogenesis-related (PR) proteins is one of the most crucial events of inducible plant defense response. Herein, we report the characterization of CaHaPR-4, a Helicoverpa-inducible class II PR-4 protein from chickpea. Bioinformatic analysis of CaHaPR-4 protein indicated the presence of a signal peptide, barwin domain but it lacks the chitin-binding site/hevein domain. The recombinant CaHaPR-4 is bestowed with RNase and bivalent ion-dependent DNase activity. Further, the RNA and DNA binding sites were identified and confirmed by analyzing interactions between mutated CaHaPR-4 with the altered active site and ribonuclease inhibitor, 5′ADP and DNase inhibitor, 2‑nitro‑5‑thiocyanobenzoic acid (NTCB) using 3D modeling and docking studies. Moreover, CaHaPR-4 shows antifungal activity as well as growth inhibiting properties against neonatal podborer larvae. To the best of our knowledge, this is the first report of a PR-4 showing RNase, DNase, antifungal and most importantly insect growth inhibiting properties against Helicoverpa armigera simultaneously.