Common Source of Cryoprotection and Osmoprotection by Osmolytes

Govrin, Roy; Obstbaum, Tal; Sivan, Uri

doi:10.1021/jacs.9b06727

Cited by 22 publications

(37 citation statements)

References 28 publications

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“…The heterogeneous impacts of osmolytes toward the stabilization of proteins present the need for an extension of recent investigations on the folding equilibrium of proteins in the presence of osmolytes at varying temperatures − and pressures , and especially in the presence of the denaturant urea. ,,, Recently, a local accumulation of TMAO was noted just outside the first solvation shell of multiple pentameric proteins in a joint simulation/experimental investigation, and more interestingly the observation remained qualitatively valid across a 500-fold increase in pressure. The action of osmolytes as a cryoprotectant (low temperature) or osmoprotectant (high pressure) or as a protectant in the presence of denaturants needs to be investigated in more detail.…”

Section: Summary and Future Directionsmentioning

confidence: 97%

Bottom-Up View of the Mechanism of Action of Protein-Stabilizing Osmolytes

Mukherjee

Mondal

2020

J. Phys. Chem. B

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The molecular mechanism of osmolytes on the stabilization of native states of protein is still controversial irrespective of extensive studies over several decades. Recent investigations in terms of experiments and molecular dynamics simulations challenge the popular osmophobic model explaining the mechanistic action of protein-stabilizing osmolytes. The current Perspective presents an updated view on the mechanistic action of osmolytes in light of resurgence of interesting experiments and computer simulations over the past few years in this direction. In this regard, the Perspective adopts a bottom-up approach starting from hydrophobic interactions and eventually adds complexity in the system, going toward the protein, in a complex topology of hydrophobic and electrostatic interactions. Finally, the Perspective unifies osmolyte-induced protein conformational equilibria in terms of preferential interaction theory, irrespective of individual preferential binding or exclusion of osmolytes depending on different osmolytes and protein surfaces. The Perspective also identifies future research directions that can potentially shape this interesting area.

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Section: Summary and Future Directionsmentioning

confidence: 97%

Bottom-Up View of the Mechanism of Action of Protein-Stabilizing Osmolytes

Mukherjee

Mondal

2020

J. Phys. Chem. B

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“…Free proline is rapidly accumulated not only in response to drought and salinity, but also to cold, heavy metals, or pathogen attack ( Hayat et al, 2012 ). Because of this variety of inducing stimuli, several other beneficial effects of proline have been hypothesized, ranging from stabilization of membranes and enzymes to reactive oxygen species scavenging, regulation of redox balance, or induction of antioxidant defenses ( Liang et al, 2013 ; Kishor and Sreenivasulu, 2014 ; Govrin et al, 2019 ; Forlani et al, 2019b ).…”

Section: Introductionmentioning

confidence: 99%

Enzymology and Regulation of δ1-Pyrroline-5-Carboxylate Synthetase 2 From Rice

2021

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Under several stress conditions, such as excess salt and drought, many plants accumulate proline inside the cell, which is believed to help counteracting the adverse effects of low water potential. This increase mainly relies upon transcriptional induction of δ1-pyrroline-5-carboxylate synthetase (P5CS), the enzyme that catalyzes the first two steps in proline biosynthesis from glutamate. P5CS mediates both the phosphorylation of glutamate and the reduction of γ-glutamylphosphate to glutamate-5-semialdehyde, which spontaneously cyclizes to δ1-pyrroline-5-carboxylate (P5C). In most higher plants, two isoforms of P5CS have been found, one constitutively expressed to satisfy proline demand for protein synthesis, the other stress-induced. Despite the number of papers to investigate the regulation of P5CS at the transcriptional level, to date, the properties of the enzyme have been only poorly studied. As a consequence, the descriptions of post-translational regulatory mechanisms have largely been limited to feedback-inhibition by proline. Here, we report cloning and heterologous expression of P5CS2 from Oryza sativa. The protein has been fully characterized from a functional point of view, using an assay method that allows following the physiological reaction of the enzyme. Kinetic analyses show that the activity is subjected to a wide array of regulatory mechanisms, ranging from product inhibition to feedback inhibition by proline and other amino acids. These findings confirm long-hypothesized influences of both, the redox status of the cell and nitrogen availability, on proline biosynthesis.

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“…Accumulation of proline (Pro) is a common physiological response of many plants to biotic and abiotic stress and is believed to play an adaptive role in plant stress tolerance (Meena et al, 2019; Verbruggen & Hermans, 2008). Recently, evidence has been presented that Pro‐stimulated signalling prevents chlorophyll degradation under water stress (Altuntaş, Demiralay, Sezgin Muslu, & Terzi, 2020), and there are reports that Pro protects enzymes by modulating electrostatic interactions and stabilizing the tertiary structure (Govrin, Obstbaum, & Sivan, 2019; Rydeen, Brustad, & Pielak, 2018). Additionally, there is evidence that Pro activates the antioxidative defense, either directly or through ROS signalling originating from mitochondrial Pro degradation (Szabados & Savouré, 2010).…”

Section: Introductionmentioning

confidence: 99%

Cytosolic proline is required for basal freezing tolerance in Arabidopsis

Hoermiller

Funck

Schönewolf

et al. 2021

Plant Cell & Environment

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The amino acid proline accumulates in many plant species under abiotic stress conditions, and various protective functions have been proposed. During cold stress, however, proline content in Arabidopsis thaliana does not correlate with freezing tolerance. Freezing sensitivity of a starchless plastidic phosphoglucomutase mutant (pgm) indicated that localization of proline in the cytosol might stabilize the plasma membrane during freeze–thaw events. Here, we show that re‐allocation of proline from cytosol to vacuole was similar in the pyrroline‐5‐carboxylate synthase 2–1 (p5cs2–1) mutant and the pgm mutant and caused similar reduction of basal freezing tolerance. In contrast, the starch excess 1–1 mutant (sex1‐1) had even lower freezing tolerance than pgm but did not affect sub‐cellular localization of proline. Freezing sensitivity of sex1‐1 mutants affected primarily the photosynthetic electron transport and was enhanced in a sex1‐1::p5cs2–1 double mutant. These findings indicate that several independent factors determine basal freezing tolerance. In a pgm::p5cs2–1 double mutant, freezing sensitivity and proline allocation to the vacuole were the same as in the parental lines, indicating that the lack of cytosolic proline was the common cause of reduced basal freezing tolerance in both mutants. We conclude that cytosolic proline is an important factor in freezing tolerance of non‐acclimated plants.

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Common Source of Cryoprotection and Osmoprotection by Osmolytes

Cited by 22 publications

References 28 publications

Bottom-Up View of the Mechanism of Action of Protein-Stabilizing Osmolytes

Bottom-Up View of the Mechanism of Action of Protein-Stabilizing Osmolytes

Enzymology and Regulation of δ1-Pyrroline-5-Carboxylate Synthetase 2 From Rice

Cytosolic proline is required for basal freezing tolerance in Arabidopsis

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