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.
Highlights
Genetic evidence supports a protective role for plant dehydrins against drought and cold
We examine here the ability of the minimal dehydrin K2 to protect liposomes from freeze-thaw and cold stress damage, what effect binding has on some membrane properties, and what effect binding has on K2 structure
The Protective Effects of K2 on Stressed Liposomes—Several previous reports have shown that dehydrins are able to interact with membranes (5, 26 –30)
Summary
Genetic evidence supports a protective role for plant dehydrins against drought and cold. Results: Dehydrins prevent membrane fusion and lower the transition temperature without altering membrane accessibility and fluidity. 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 freezethaw treatment. 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 segments play no role in binding or protection
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