Deciphering a mechanism of membrane permeabilization by α-hordothionin peptide.

α-Hordothionin (αHTH) belongs to thionins, the plant antimicrobial peptides with membrane-permeabilizing activity which is associated with broad-range antimicrobial activity. Experimental data have revealed a phospholipid-binding site and indicated formation of ion channels as well as membrane disruption activity of thionin. However, the mechanism of membrane permeabilization by thionin remained unknown.

Structural changes induced in thionins by chloride anions as determined by molecular dynamics simulations.

Computational analysis of two membrane-permeabilizing peptides, barley alpha-hordothionin and wheat beta-purothionin, revealed that anions can trigger dynamic and structural changes in the thionin antiparallel double alpha-helix core. Analysis of the molecular dynamics simulations demonstrated that anions induced unfolding of the alpha2 and alpha1 helices at the carboxyl ends which are located on the opposite ends of the alpha-helix core. An internalized water molecule was observed inside the unfolded alpha2 C-end.

Is there a difference in metal ion-based inhibition between members of thionin family: Molecular dynamics simulation study.

Thionins have a considerable potential as antimicrobial compounds although their application may be restricted by metal ion-based inhibition of membrane permeabilizing activity. We previously reported the properties associated with the proposed mechanism of metal ion-based inhibition of beta-purothionin. In this study, we investigated the effects of metal ions on alpha-hordothionin which differs from beta-purothionin by eight out of 45 residues.

Mechanism of beta-purothionin antimicrobial peptide inhibition by metal ions: molecular dynamics simulation study.

Wheat beta-purothionin is a highly potent antimicrobial peptide which, however, is inactivated by metal ions. The key structural properties and mechanisms of inhibition of beta-purothionin were investigated for the first time using unconstrained molecular dynamics simulations in explicit water. A series of simulations were performed to determine effects of temperature and the metal ions.