Probing the potential of a charge-based stabilizing interaction between the vitis riparia YSK2 dehydrin and yeast frataxin homologue 1

Smith, Margaret
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University of Guelph

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.

dehydrin, cold denaturation, macromolecule cryoprotection