title: Molecular dynamics simulations and CD spectroscopy reveal hydration-induced unfolding of the intrinsically disordered LEA proteins COR15A and COR15B from Arabidopsis thaliana.
abstract: The LEA (late embryogenesis abundant) proteins COR15A and COR15B from Arabidopsis thaliana are intrinsically disordered under fully hydrated conditions, but obtain α-helical structure during dehydration, which is reversible upon rehydration. To understand this unusual structural transition, both proteins were investigated by circular dichroism (CD) and molecular dynamics (MD) approaches. MD simulations showed unfolding of the proteins in water, in agreement with CD data obtained with both HIS-tagged and untagged recombinant proteins. Mainly intramolecular hydrogen bonds (H-bonds) formed by the protein backbone were replaced by H-bonds with water molecules. As COR15 proteins function in vivo as protectants in leaves partially dehydrated by freezing, unfolding was further assessed under crowded conditions. Glycerol reduced (40%) or prevented (100%) unfolding during MD simulations, in agreement with CD spectroscopy results. H-bonding analysis indicated that preferential exclusion of glycerol from the protein backbone increased stability of the folded state.
authors.affiliation: Center for Bioinformatics and Molecular Simulations, Universidad de Talca, 2 Norte 685, Casilla 721, Talca, Chile. wgonzalez@utalca.cl (Wendy González, for correspondence relating to protein modelling).
authors.forename: Carlos
authors.initials: C
authors.lastname: Navarro-Retamal
authors.forename: Anne
authors.initials: A
authors.lastname: Bremer
authors.forename: Jans
authors.initials: J
authors.lastname: Alzate-Morales
authors.forename: Julio
authors.initials: J
authors.lastname: Caballero
authors.forename: Dirk K
authors.initials: DK
authors.lastname: Hincha
authors.forename: Wendy
authors.initials: W
authors.lastname: González
authors.forename: Anja
authors.initials: A
authors.lastname: Thalhammer
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry*; D029681:Arabidopsis Proteins / Q000737:chemistry*; D002942:Circular Dichroism; D006860:Hydrogen Bonding; D056004:Molecular Dynamics Simulation; D010936:Plant Extracts / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D017433:Protein Structure, Secondary; D058767:Protein Unfolding
chemical_list: D029681:Arabidopsis Proteins; C116166:COR15 protein, Arabidopsis; D010936:Plant Extracts