Structural Plasticity of Intrinsically Disordered LEA Proteins from Xerophyta schlechteri Provides Protection In Vitro and In Vivo

Abstract

Late embryogenesis abundant (LEA) proteins are essential to the ability of resurrection plants and orthodox seeds to protect the subcellular milieu against irreversible damage associated with desiccation. In this work, we investigated the structure and function of six LEA proteins expressed during desiccation in the monocot resurrection species Xerophyta schlechteri (XsLEAs). In silico analyses suggested that XsLEAs are hydrophilic proteins with variable intrinsically disordered protein (IDP) properties. Circular dichroism (CD) analysis indicated that these proteins are mostly unstructured in water but acquire secondary structure in hydrophobic solution, suggesting that structural dynamics may play a role in their function in the subcellular environment. The protective property of XsLEAs was demonstrated by their ability to preserve the activity of the enzyme lactate dehydrogenase (LDH) against desiccation, heat and oxidative stress, as well as growth of Escherichia coli upon exposure to osmotic and salt stress. Subcellular localization analysis indicated that XsLEA recombinant proteins are differentially distributed in the cytoplasm, membranes and nucleus of Nicotiana benthamiana leaves. Interestingly, a LEA_1 family protein (XsLEA1-8), showing the highest disorder-to-order propensity and protective ability in vitro and in vivo, was also able to enhance salt and drought stress tolerance in Arabidopsis thaliana. Together, our results suggest that the structural plasticity of XsLEAs is essential for their protective activity to avoid damage of various subcellular components caused by water deficit stress. XsLEA1-8 constitutes a potential model protein for engineering structural stability in vitro and improvement of water-deficit stress tolerance in plants.

Review of the current state of protein aggregation inhibition from a materials chemistry perspective: special focus on polymeric materials

“…417 Multiple studies have demonstrated the ability of LEA proteins to protect biological entities such as proteins and membranes in desiccating environments. 400,[418][419][420][421][422] In one such study, Goyal et al reported that recombinant forms of AavLEA1, a group 3 LEA protein, can protect against desiccation induced aggregation of citrate synthase (CS), and helps retain its activity. 401 They hypothesized that owing to an unordered and flexible structure, LEA proteins can act as a molecular shield, thus forming a physical barrier to suppress any contact between CS molecules.…”

Exploratory Study of Fatty Acid Profile in Two Filmy Ferns with Contrasting Desiccation Tolerance Reveal the Production of Very Long Chain Polyunsaturated Omega-3 Fatty Acids

“…It may rely on the presence of particular minor VLCFAs such as 8,11,14eicosatrienoic acid (C20:3n6) and 4,7,10.13.16,19-docosahexaenoic acid (C22:6n3), which exhibited higher contents in H. plicatum than H. caudiculatum and others only detected in H. plicatum such as 13-docosenoic acid (C22:1n9) and 15-tetracosenoic acid (C24:1n9) fatty acids. Another alternative explanation besides this lipid profile, is the interaction of membranes with other biochemical membrane stabilizers such as the amphipathic LEA proteins or sugar-alcohols, such as those Plants 2019, 8, x; doi: FOR PEER REVIEW www.mdpi.com/journal/plants observed in Xerophyta schlechteri [47] or Pitcairnia burchellii [48]. It is likely that a more complex hypothesis should be invoked to explain our observations regarding differences in membrane stability observed between these two filmy ferns species ( Figure 2) contrasting in their desiccation tolerance.…”

The N-Terminal Region of Soybean PM1 Protein Protects Liposomes during Freeze-Thaw

“…There is relatively little research on the protective roles of other groups, including the LEA_1 proteins, which are highly expressed in mature seeds and also accumulate in vegetative tissues under stress conditions [ 4 , 5 , 6 ]. Some genetic studies have been performed showing that the over-expression of LEA_1 genes, such as LEA4-1 from Brassica napus , BhLEA1 and BhLEA2 from Boea hygrometrica , AtLEA4-5 from Arabidopsis thaliana , and XsLEA1-8 from Xerophyta schlechteri , confer tolerance to salt, drought and osmotic stress in transgenic plants [ 5 , 6 , 7 ]. The over-expression of recombinant Gastrodia elata GeLEA1-1 or Xerophyta schlechteri XsLEA1-8 enhances Escherichia coli viability under low-temperature or heat stress [ 7 , 8 ].…”

“…Some genetic studies have been performed showing that the over-expression of LEA_1 genes, such as LEA4-1 from Brassica napus , BhLEA1 and BhLEA2 from Boea hygrometrica , AtLEA4-5 from Arabidopsis thaliana , and XsLEA1-8 from Xerophyta schlechteri , confer tolerance to salt, drought and osmotic stress in transgenic plants [ 5 , 6 , 7 ]. The over-expression of recombinant Gastrodia elata GeLEA1-1 or Xerophyta schlechteri XsLEA1-8 enhances Escherichia coli viability under low-temperature or heat stress [ 7 , 8 ]. In addition, in vitro, the recombinant LEA_1 proteins AtLEA4-2 and AtLEA4-5 (both A. thaliana ) and XsLEA1-8 can preserve lactate dehydrogenase activity and prevent this enzyme aggregating during freeze–thaw, heat, desiccation and oxidative stress [ 7 , 9 , 10 ].…”

“…The over-expression of recombinant Gastrodia elata GeLEA1-1 or Xerophyta schlechteri XsLEA1-8 enhances Escherichia coli viability under low-temperature or heat stress [ 7 , 8 ]. In addition, in vitro, the recombinant LEA_1 proteins AtLEA4-2 and AtLEA4-5 (both A. thaliana ) and XsLEA1-8 can preserve lactate dehydrogenase activity and prevent this enzyme aggregating during freeze–thaw, heat, desiccation and oxidative stress [ 7 , 9 , 10 ]. Liu et al suggested that BhLEA1 and BhLEA2 play a general protective role in the plant cell during dehydration stress and increase membrane and protein stability, as indicated by the relatively low electrolyte leakage and higher SOD and POD activity in transgenic plant leaves [ 5 ].…”