Sequence composition versus sequence order in the cryoprotective function of an intrinsically disordered stress‐response protein

Abstract

Intrinsically disordered stress proteins have been shown to act as chaperones, protecting proteins from damage caused by stresses such as freezing and thawing. Dehydration proteins (dehydrins) are intrinsically disordered stress proteins that are found in almost all land plants. They consist of a variable number of the short, semi-conserved, Y-, S-, and K-segments, with longer stretches of poorly conserved sequences in between. Previous studies have provided conflicting views on the details of the dehydrin cryoprotective mechanism of enzymes. Experiments with polyethylene glycol (PEG) have shown that PEG cryoprotective efficiency is the same as dehydrins of the same hydrodynamic radius, suggesting that the protein's disordered and polar nature is important, rather than the specific order of the residues. To further elucidate the mechanism, we created scrambled variants of the wild grape dehydrins K 2 and YSK 2 and tested their ability to protect lactate dehydrogenase and yeast frataxin homolog-1 from freeze/thaw damage. The results show that for preventing aggregation, it is the sequence composition and the size of the dehydrin that is the most important factor in protection, while for freeze/thaw damage causing loss of secondary structure, it is the sequence composition that is most significant.

Presence of intrinsically disordered proteins can inhibit the nucleation phase of amyloid fibril formation of Aβ(1–42) in amino acid sequence independent manner

“…The examples include N-terminal disordered peptides derived from bovine prion protein precursor (bPrP), PrP (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) and PrP(108-119) 38 . However, we did not find any sequence similarity among IDP-D10, PrP (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), or PrP(108-119). Notably, IDP-D10 is a partial sequence of TNFRSF11B, which, www.nature.com/scientificreports/ unlike bPrP, is not expressed in the brain.…”

“…Molecular shielding may decrease stochastic self-collisions between target enzyme molecules during the occasional high concentrations occurring in repeated freeze–thaw cycles 21 . Two research groups have reported that a weak but clear correlation between the cryoprotective activity of various DHN segments and their mutants versus their hydrodynamic radius (Rh), whereas their amino acid compositions or sequences were not relevant 21 , 26 , 28 , 29 . We succeeded in expanding the concept of the molecular shield by showing that it is independent of the amino acid sequence and only depends on the intrinsic disorder of the protein.…”

Protecting Enzymes from Stress-Induced Inactivation

“…25,26,28 In vitro , LEA proteins protect LDH, fumarase, and citrate synthase activity and inhibit the latter’s aggregation. 24,26,28,50,62,64,65 Additionally, formulation with LEA proteins reduces the loss of fluorescence of the red fluorescent protein mCherry upon vacuum-drying and rehydration. 26…”

Genomic diversification of dehydrin gene family in vascular plants: three distinctive orthologue groups and a novel KS-dehydrin conserved protein motif

“…It has been observed that the cryoprotective capacity of DHNs depends on the size (hydrodynamic radius) and the intrisic disorder, highlighting the importance of the composition and size of the Phi segments, which are generally less conserved than the structural motifs 61 . It has been also demonstrated that it is the size and sequence composition of DHNs that is the most important for preventing aggregation, while for freeze damage it is the sequence composition that is most significant 62 . Thus, it seems that the simple presence of K and S segments would not be necessarily good predictors of the functional characteristics of DHNs.…”