Function in disorder: A review on the roles of the disordered dehydrin proteins in conferring stress tolerance

Water scarcity as a result of drought is considered to be among the most common forms of abiotic stress which directly hampers plant health. Such conditions often lead to various interlinked physiological conditions, including oxidative stress resulting from increased ROS levels that in turn, induce membranes dysfunction, leading to disruption in cellular ionic balance, and oxidation of macromolecules. Plants employ several mechanisms to counter these hostile conditions, which help them adapt to such unforgiving environments. Accumulation of specific types of proteins called dehydrins (DHNs) represents one such mechanism of adaptation. DHNs are ubiquitous in distribution and have been reported in different life forms; accumulating under a wide spectrum of stress. An important role of DHNs is to protect and maintain cell's macromolecular structure and function, thereby preserving membrane integrity, stabilizing proteins and nucleic acid, and conferring protection against oxidative stress. The present article explores different aspects of DHNs, including their structural compositions, architectures and conformational flexibility, and their role in combating a plethora of stress environments, with specific focus towards drought. Possible involvements of DHNs in intracellular biocondensates formation through phase separation and their role in stress sensing are also provided.