Probing the potential of a charge-based stabilizing interaction between the vitis riparia YSK2 dehydrin and yeast frataxin homologue 1
Dehydrins are intrinsically disordered proteins expressed throughout the plant kingdom in response to low intracellular water. They likely act as macromolecule cryoprotectants. The impact of the charge distribution of a YSK2 dehydrin from Vitis riparia on the stability of yeast frataxin homologue 1 (Yfh1) at 1˚C was examined using circular dichroism spectroscopy. Three mutant YSK2-constructs were created: YSK2-SpaceK (evenly distributed positive charge), YSK2-Neut (locally neutralized charge), and YSK2-K→R (lysine substituted for arginine). The cryoprotective efficiency of these constructs in addition to a fourth, YSK2-φ→T (specific hydrophobic residues substituted with threonine) were also compared in a lactate dehydrogenase (LDH) activity assay. Charge distribution appears to be an important part of the cryoprotective mechanism of dehydrins with respect to Yfh1 but not LDH, where hydrodynamic radius is a more significant factor. This is suggestive of a charge-based interaction between YSK2 and Yfh1 that should be studied in greater detail in future work.