The Disordered Dehydrin and Its Role in Plant Protection: A Biochemical Perspective

Abstract

Dehydrins are intrinsically disordered proteins composed of several well conserved sequence motifs known as the Y-, S-, F-, and K-segments, the latter of which is a defining feature of all dehydrins. These segments are interspersed by regions of low sequence conservation and are organized modularly, which results in seven different architectures: K_n, SK_n, Y_nSK_n, Y_nK_n, K_nS, F_nK and F_nSK_n. Dehydrins are expressed ubiquitously throughout the plant kingdom during periods of low intracellular water content, and are capable of improving desiccation tolerance in plants. In vitro evidence of dehydrins shows that they are involved in the protection of membranes, proteins and DNA from abiotic stresses. However, the molecular mechanisms by which these actions are achieved are as of yet somewhat unclear. With regards to macromolecule cryoprotection, there is evidence to suggest that a molecular shield-like protective effect is primarily influenced by the hydrodynamic radius of the dehydrin and to a lesser extent by the charge and hydrophobicity. The interaction between dehydrins and membranes is thought to be a surface-level, charge-based interaction that may help to lower the transition temperature, allowing membranes to maintain fluidity at low temperatures and preventing membrane fusion. In addition, dehydrins are able to protect DNA from damage, showing that these abiotic stress protection proteins have multiple roles.

Keywords: abiotic stress; cryoprotection; dehydration; dehydrins; intrinsically disordered; structure.

Figure 1

In vitro evidence suggests that dehydrins are involved in the binding and stabilization of DNA and membranes, as well as in the cryoprotection of proteins. Depicted here are representations of the interactions thought to take place in these scenarios. The K₂ dehydrin from Vitis riparia is shown in different conformations that it samples (alone in the center, extended and parallel to DNA, and acting as a crowder around lactate dehydrogenase).