title: Interactions of Thellungiella salsuginea dehydrins TsDHN-1 and TsDHN-2 with membranes at cold and ambient temperatures-surface morphology and single-molecule force measurements show phase separation, and reveal tertiary and quaternary associations.
abstract: Dehydrins (group 2 late embryogenesis abundant proteins) are intrinsically-disordered proteins that are expressed in plants experiencing extreme environmental conditions such as drought or low temperature. Their roles include stabilizing cellular proteins and membranes, and sequestering metal ions. Here, we investigate the membrane interactions of the acidic dehydrin TsDHN-1 and the basic dehydrin TsDHN-2 derived from the crucifer Thellungiella salsuginea that thrives in the Canadian sub-Arctic. We show using compression studies with a Langmuir-Blodgett trough that both dehydrins can stabilize lipid monolayers with a lipid composition mimicking the composition of the plant outer mitochondrial membrane, which had previously been shown to induce ordered secondary structures (disorder-to-order transitions) in the proteins. Ellipsometry of the monolayers during compression showed an increase in monolayer thickness upon introducing TsDHN-1 (acidic) at 4°C and TsDHN-2 (basic) at room temperature. Atomic force microscopy of supported lipid bilayers showed temperature-dependent phase transitions and domain formation induced by the proteins. These results support the conjecture that acidic dehydrins interact with and potentially stabilize plant outer mitochondrial membranes in conditions of cold stress. Single-molecule force spectroscopy of both proteins pulled from supported lipid bilayers indicated the induced formation of tertiary conformations in both proteins, and potentially a dimeric association for TsDHN-2.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada.
authors.forename: Luna N
authors.initials: LN
authors.lastname: Rahman
authors.forename: Fraser
authors.initials: F
authors.lastname: McKay
authors.forename: Maximiliano
authors.initials: M
authors.lastname: Giuliani
authors.forename: Amanda
authors.initials: A
authors.lastname: Quirk
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Moffatt
authors.forename: George
authors.initials: G
authors.lastname: Harauz
authors.forename: John R
authors.initials: JR
authors.lastname: Dutcher
mesh_terms: D000595:Amino Acid Sequence; D001703:Biophysics / Q000379:methods; D019607:Brassicaceae / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003080:Cold Temperature; D019281:Dimerization; D008055:Lipids / Q000737:chemistry; D018625:Microscopy, Atomic Force / Q000379:methods; D015233:Models, Statistical; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000378:metabolism / Q000502:physiology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature
chemical_list: D008055:Lipids; D010940:Plant Proteins; D011994:Recombinant Proteins; C070556:dehydrin proteins, plant