Metal ions provide structural stability and compactness to tetrameric purothionin

Abstract

Antimicrobial plant protein purothionin plays a significant role in immunity and microbial defense systems in plants and animals. From the molecular simulation analyses and spectroscopic investigation, it was observed that the structural arrangement of the protein tetramer attained much more stable and compact conformation in the presence of calcium and magnesium compared to the tetramer alone in the absence of ions. An increase in the folded secondary structure in the presence of calcium and magnesium ions was observed. The circular dichroism spectral analysis and FT-IR study along with molecular dynamics simulation studies suggested some increase in the helical content/compactness of the protein. Structural stability of the protein, as observed, may be linked to increased antifungal activity against pathogens like Candida albicans, Candida krusei and Candida parapsilosis.