title: Structural and Functional Insights into the Cryoprotection of Membranes by the Intrinsically Disordered Dehydrins.
abstract: Dehydration can be due to desiccation caused by a lack of environmental water or to freezing caused by a lack of liquid water. Plants have evolved a large family of proteins called LEA (late embryogenesis abundant) proteins, which include the intrinsically disordered dehydrin (dehydration protein) family, to combat these abiotic stresses. Although transcription and translation studies have shown a correlation between dehydration stress and the presence of dehydrins, the biochemical mechanisms have remained somewhat elusive. We examine here the effect and structure of a small model dehydrin (Vitis riparia K2) on the protection of membranes from freeze-thaw stress. This protein is able to bind to liposomes containing phosphatidic acid and protect the liposomes from fusing after freeze-thaw treatment. The presence of K2 did not measurably affect liposome surface accessibility or lipid mobility but did lower its membrane transition temperature by 3 °C. Using sodium dodecyl sulfate as a membrane model, we examined the NMR structure of K2 in the presence and absence of the micelle. Biochemical and NMR experiments show that the conserved, lysine-rich segments are involved in the binding of the dehydrin to a membrane, whereas the poorly conserved φ segments play no role in binding or protection.
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Clarke
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Kelly F
authors.initials: KF
authors.lastname: Boddington
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Josephine M
authors.initials: JM
authors.lastname: Warnica
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: John
authors.initials: J
authors.lastname: Atkinson
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: McKenna
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Madge
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
authors.forename: Christine H
authors.initials: CH
authors.lastname: Barker
authors.affiliation: Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. Electronic address: graether@uoguelph.ca.
authors.forename: Steffen P
authors.initials: SP
authors.lastname: Graether
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D003451:Cryoprotective Agents / Q000737:chemistry* / Q000378:metabolism*; D064267:Intrinsically Disordered Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008081:Liposomes / Q000737:chemistry; D008823:Micelles; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D055672:Static Electricity; D044366:Transition Temperature; D027843:Vitis / Q000235:genetics / Q000378:metabolism
chemical_list: D003451:Cryoprotective Agents; D064267:Intrinsically Disordered Proteins; D008081:Liposomes; D008823:Micelles; D010940:Plant Proteins; C070556:dehydrin proteins, plant
keywords: circular dichroism (CD); cold stress; dehydrin; freeze/thaw; intrinsically disordered protein; liposome; membrane fusion; nuclear magnetic resonance (NMR)4; protein structure; stress