Physiological, Structural, and Functional Insights Into the Cryoprotection of Membranes by the Dehydrins

Abstract

Plants can be exposed to cold temperatures and have therefore evolved several mechanisms to prevent damage caused by freezing. One of the most important targets are membranes, which are particularly susceptible to cold damage. To protect against such abiotic stresses, plants express a family of proteins known as late embryogenesis abundant (LEA) proteins. Many LEA proteins are intrinsically disordered, that is, they do not contain stable secondary or tertiary structures alone in solution. These proteins have been shown in a number of studies to protect plants from damage caused by cold, drought, salinity, and osmotic stress. In this family, the most studied proteins are the type II LEA proteins, better known as dehydrins (dehydration-induced proteins). Many physiological studies have shown that dehydrins are often located near the membrane during abiotic stress and that the expression of dehydrins helps to prevent the formation of oxidation-modified lipids and reduce the amount of electrolyte leakage, two hallmarks of damaged membranes. One of the earliest biophysical clues that dehydrins are involved in membrane cryoprotection came from in vitro studies that demonstrated a binding interaction between the protein and membranes. Subsequent work has shown that one conserved motif, known as K-segments, is involved in binding, while recent studies have used NMR to explore the residue specific structure of dehydrins when bound to membranes. The biophysical techniques also provide insight into the mechanism by which dehydrins protect the membrane from cold stress, which appears to mainly involve the lowering of the transition temperature.

Comparative Analysis of Dehydrins from Woody Plant Species

“…The core sequence (Lys-Ile-Lys-Glu) is crucial for cryoprotection, as any changes in this sequence that lead to the loss of hydrophobicity cause a significant reduction in their cryoprotective activity [ 27 , 28 ]. Moreover, the positive charge facilitates the binding of dehydrins to negatively charged intracellular components, such as cell membranes, providing protection under low-temperature conditions [ 28 , 29 , 30 ]. We have found some dehydrins with the K segments flanked by His-His residues ( Table 1 and Table S1 ), a configuration believed to enhance interactions between the K segment and membranes in a pH-dependent manner [ 31 ].…”

Protein structure–function continuum model: Emerging nexuses between specificity, evolution, and structure

“…IDPs/IDRs are also involved in synaptic vesicle trafficking and exocytosis and in overall synaptic organization (Snead & Eliezer, 2019). Intrinsically disordered dehydrins are important for cryoprotection of membranes (Murray & Graether, 2022). Overall, because of a crucial importance of a dynamic cross‐talk and complex interplay between the IDPs/IDRs and the membranes, where disorder plays a number of essential roles in membrane modulation, lipid and curvature sensing, phase separation events, transduction of signal across membranes, protein scaffolding, and in the coupling of enzymatic activity to these processes, it was claimed: “Far from being a marriage of convenience, intrinsically disordered regions and membranes are a match made in heaven for cell signalling” (Cornish et al, 2020).…”

Plant biomarkers as early detection tools in stress management in food crops: a review

“…The S-segment is responsible for phosphorylation by the SNF1-related protein kinase, which influences the translocation of dehydrins from the cytosol to the nucleus and binding to calcium ions. However, the precise function of the Y-segment remains unknown (Murray and Graether 2022 ). Stival and colleagues reported the expression of dehydrin genes in Picea glauca in response to drought.…”