Study of Molecular Interaction Between Arabidopsis Aquaporin and Pseudomonas syringae pv. syringae Harpin (HrpZPss) Through Molecular Docking Tools

Abstract

Harpins constitute one unique group of elicitor proteins secreted through the type 3 secretion system during plant-pathogen interactions and induce various responses like the formation of pores in the membrane, hypersensitive response, and systemic acquired resistance in non-host plants. Harpins from different bacterial sources elicit different responses in plants which may be due to their structural differences. As of today, the complete mechanisms of action of different harpins are lacking. The present study aimed to investigate the protein-protein-mediated functional association between members of the aquaporin PIP family from Arabidopsis thaliana and harpin (HrpZPss) from Pseudomonas syringae pv. syringae through an in-silico molecular docking approach using ZDOCK. We identified a motif (HINPAVTFG) present in AtPIP1;3 as a functional signature sequence. Most of the residues from this signature sequence showed
a positive and close interaction with the HrpZPss protein. The quality assessment and residues-wise fluctuation of the selected protein were analyzed with the help of molecular docking. The stability of predicted models of docked complexes (AtPIP1;3, HrpZPss and HrpZPss-AtPIP1;3 complexes) were checked by molecular dynamics simulations using WEBGRO. The RMSD values of AtPIP1;3, HrpZPss, and HrpZPss-AtPIP1;3 complexes were calculated at 50 ns. The stable conformation of the AtPIP1;3 and HrpZPss were observed at 14.1 and 13.2 ns, respectively, while the stability of the HrpZPss-AtPIP1;3 complex was achieved at 20 ns. The present in-silico analysis demonstrates a positive interaction between harpin (HrpZPss) and aquaporin (AtPIP1;3) which would help in understanding the harpininduced signaling responses in non-host plants.