title: Mechanism of beta-purothionin antimicrobial peptide inhibition by metal ions: molecular dynamics simulation study.
abstract: 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. Analyses of the unconstrained simulations allowed the experimentally unavailable structural and dynamic details to be unambiguously examined. The global fold and the alpha1 helix of beta-purothionin are thermally stable and not affected by metal ions. In contrast, the alpha2 helix unfolds with shift of temperature from 300 K and in the presence of metal ions. The network of conserved residues including Arg30 and Lys5 is sensitive to environmental changes and triggers unfolding. Loop regions display high flexibility and elevated dynamics, but are affected by metal ions. Our study provides insights into the mechanism of metal ion-based inhibition.
authors.affiliation: LSU AgCenter Biotechnology Laboratory, Louisiana State University, 115 Wilson Building, LSU, Baton Rouge, LA, 70803, USA. soard@agctr.lsu.edu
authors.forename: Svetlana
authors.initials: S
authors.lastname: Oard
authors.forename: Bijaya
authors.initials: B
authors.lastname: Karki
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry* / Q000378:metabolism; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000378:metabolism; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D008670:Metals / Q000494:pharmacology*; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D013696:Temperature; D014118:Toxins, Biological; D014867:Water / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D008670:Metals; D010446:Peptide Fragments; D010940:Plant Proteins; D014118:Toxins, Biological; D014867:Water; C016085:purothionin