Abstract
Dehydrins belongs to a large group of highly hydrophilic proteins known as Late Embryogenesis Abundant (LEA) proteins. It is well known that dehydrins are intrinsically disordered plant proteins that accumulate during the late stages of embryogenesis and in response to abiotic stresses; however, the molecular mechanisms by which their functions are carried out are still unclear. We have previously reported that transgenic Arabidopsis plants overexpressing an Opuntia streptacantha SK3 dehydrin (OpsDHN1) show enhanced tolerance to freezing stress. Herein, we show using a split-ubiquitin yeast two-hybrid system that OpsDHN1 dimerizes. We found that the deletion of regions containing K-segments and the histidine-rich region in the OpsDHN1 protein affects dimer formation. Not surprisingly, in silico protein sequence analysis suggests that OpsDHN1 is an intrinsically disordered protein, an observation that was confirmed by circular dichroism and gel filtration of the recombinantly expressed protein. The addition of zinc triggered the association of recombinantly expressed OpsDHN1 protein, likely through its histidine-rich motif. These data brings new insights about the molecular mechanism of the OpsDHN1 SK3-dehydrin.
Highlights
Plants have developed a wide variety of mechanisms to cope with environmental stresses; one response to these adverse conditions is the activation of a group of stress response genes, including Late Embryogenesis Abundant (LEAs) proteins
We have previously reported that transgenic Arabidopsis plants overexpressing an Opuntia streptacantha SK3 dehydrin (OpsDHN1) show enhanced tolerance to freezing stress
We have previously reported that transgenic Arabidopsis plants overexpressing Opuntia streptacantha SK3 DHN (OpsDHN1) show enhanced tolerance to freezing stress (Ochoa-Alfaro et al, 2012)
Summary
Plants have developed a wide variety of mechanisms to cope with environmental stresses; one response to these adverse conditions is the activation of a group of stress response genes, including Late Embryogenesis Abundant (LEAs) proteins. All members of the DHN family possess at least one amphipathic α-helix forming domain named the K-segment (EKKGIMDKIKEKLPG), which can interact with macromolecules and specific membrane regions to protect them against damage (Koag et al, 2009). Other conserved motifs such as the S- and Y-segments, and the φsegment, have been described in this group of proteins. The φ-segments are poorly conserved in sequence and length; these segments are important to maintain the unstructured state and the cryoprotective activities of DHNs (Close, 1996, 1997; Hughes and Graether, 2011)
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