Brachypodium Antifreeze Protein Gene Products Inhibit Ice Recrystallisation, Attenuate Ice Nucleation, and Reduce Immune Response

Juurakko, Collin L.; diCenzo, George C.; Walker, Virginia K.

doi:10.3390/plants11111475

Cited by 6 publications

(3 citation statements)

References 59 publications

(96 reference statements)

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“…Several cold-induced genes, including AmCIP [10], AmLEA, AmEBP1 [11], and AmCaM [12], have been isolated and functionally characterized via ectopic expression. In addition, several antifreeze proteins proposed to contribute to the freezing tolerance of A. mongolicus have been purified, and their antifreeze activities have been determined [13,14]. These studies demonstrate the efficacy of using A. mongolicus to identify cold stress tolerance-related genes.…”

Section: Introductionmentioning

confidence: 89%

Proteomic Analysis of the Cold Stress Response of Ammopiptanthus mongolicus Reveals the Role of AmCHIA in Its Cold Tolerance

Li,

Liu,

et al. 2023

Horticulturae

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Ammopiptanthus mongolicus, a traditional ethnic medicinal herb, is a rare broad-leaved evergreen shrub in the arid region of central Asia that can survive under extremely low temperatures during winter. In this study, we investigated the cold stress response of A. mongolicus leaves using physiological and proteomic approaches. Cold stress treatment increased the relative electrolyte leakage, proline, and soluble sugar levels and decreased the chlorophyll content in A. mongolicus leaves. Moreover, 93 differentially abundant proteins (DAPs) were identified using two-dimensional electrophoresis, of which 79 were further confirmed via tandem mass spectrometric analysis. The predicted functions of DAPs were mainly associated with photosynthesis in chloroplasts, reactive oxygen species scavenging, defense, and protein synthesis, folding, and degradation. A. mongolicus chitinase A (AmCHIA) is a cold-induced apoplast protein whose transcription is upregulated under cold, osmotic, high-salinity, and mechanical stresses. Recombinant AmCHIA expressed in Escherichia coli exhibits chitinase activity. Here, AmCHIA expression enhanced the cold tolerance of E. coli cells, suggesting that it may contribute to the cold adaptation of A. mongolicus after cold treatment. The present study not only provides important data for understanding the cold stress responses in plants but also serves as a basis for further exploration of the biological functions of cold-induced proteins in A. mongolicus using genetic approaches.

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Section: Introductionmentioning

confidence: 89%

Proteomic Analysis of the Cold Stress Response of Ammopiptanthus mongolicus Reveals the Role of AmCHIA in Its Cold Tolerance

Li,

Liu,

et al. 2023

Horticulturae

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“…It has also been shown that INP activity is affected by pH, which is consistent with a role for electrostatic interactions (19). We and others have suggested that INPs may multimerize through salt-bridging of the sidechains in these positions of the coil (8, 20).…”

Section: Introductionmentioning

confidence: 99%

Ice nucleation proteins self-assemble into large fibres to trigger freezing at near 0 °C

Hansen,

Lee,

Reicher

et al. 2023

Preprint

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Ice nucleating bacteria like Pseudomonas borealis (Pb) can trigger frost formation at temperatures as high as -2 C. The efficiency of ice formation by these bacteria comes from the ability of their >100 kDa ice nucleation proteins (INPs) to form ~10 MDa multimers. The INP monomers contain an array of tandem repeats, each of which is predicted to form a single coil in a B-solenoid. The 12 coils at the C-terminal end of the INP differ from the other 53 coils in lacking water organizing motifs and by having arginines on one side of the solenoid in place of acidic residues. Here we show that these arginine-containing coils (R-coils) are a distinct subdomain that, along with the adjacent putative 41-residue capping structure, facilitate INP multimerization. Bioinformatic analyses show that the cap structure is highly conserved, as is the number of R-coils. Indeed, the loss of just a few R-coils eliminated ice-nucleation activity, as did mutations designed to spoil the fold of the capping structure. Movement of the R-coils to the N-terminal end or to the middle of the B-solenoid caused a large decrease in ice nucleation temperature. Replacing the arginines with acidic residues decreased the nucleation temperature. Activity was restored when these residues were in turn replaced by lysines. A role for electrostatic interactions in INP self-assembly was suggested by the effect of pH on ice nucleation activity in bacterial lysates. This activity declined by 3-6 C at pH values below 5.0. When the INP-producing E. coli were examined by cryo-electron tomography, the cell cytoplasm contained clusters of 100 to 200 nm-long and ~5 nm-wide fibres that were absent from control bacteria. Each fibre is wide enough to have up to two INPs in cross-section and is long enough to span several INPs end to end. The ice nucleation activity in the lysates was remarkably resistant to heat treatment up to ~70 C, above which there was a slight decline with increasing temperature. Even after heating to 99 C, the lysate ice nucleation activity only lost ~8 C. We suggest that the R-coils play a crucial role in INP fibre assembly and that a bundle of these fibers could amass a sufficient number of ice-like water molecules to initiate ice nucleation at high sub-zero temperatures.

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“…It has also been shown that INP activity is affected by pH, which is consistent with a role for electrostatic interactions ( Schwidetzky et al, 2021 ). We and others have suggested that INPs may multimerize through salt-bridging of the side chains in these positions of the coil ( Forbes et al, 2022 ; Juurakko et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Ice nucleation proteins self-assemble into large fibres to trigger freezing at near 0 °C

Hansen,

Lee,

Reicher

et al. 2023

eLife

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In nature, frost can form at a few degrees below zero Celsius. However, this process requires the assembly of tens of thousands of ice-like water molecules that align together to initiate freezing at these relatively high temperatures. Water ordering on this scale is mediated by the ice nucleation proteins of common environmental bacteria like Pseudomonas syringae and P. borealis. However, individually, these 100-kDa proteins are too small to organize enough water molecules for frost formation, and it is not known how giant, megadalton-sized multimers, which are crucial for ice nucleation at high sub-zero temperatures, form. The ability of multimers to self-assemble was suggested when the transfer of an ice nucleation protein gene into E. coli led to efficient ice nucleation. Here we demonstrate that a positively-charged sub-domain at the C-terminal end of the central beta-solenoid of the ice nucleation protein is crucial for multimerization. Truncation, relocation, or change of the charge of this subdomain caused a catastrophic loss of ice nucleation ability. Cryo-electron tomography of the recombinant E. coli showed that the ice nucleation protein multimers form fibres that are ∼ 5 nm across and up to 200 nm long. A model of these fibres as an overlapping series of antiparallel dimers can account for all their known properties and suggests a route to making cell-free ice nucleators for biotechnological applications.

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Brachypodium Antifreeze Protein Gene Products Inhibit Ice Recrystallisation, Attenuate Ice Nucleation, and Reduce Immune Response

Cited by 6 publications

References 59 publications

Proteomic Analysis of the Cold Stress Response of Ammopiptanthus mongolicus Reveals the Role of AmCHIA in Its Cold Tolerance

Proteomic Analysis of the Cold Stress Response of Ammopiptanthus mongolicus Reveals the Role of AmCHIA in Its Cold Tolerance

Ice nucleation proteins self-assemble into large fibres to trigger freezing at near 0 °C

Ice nucleation proteins self-assemble into large fibres to trigger freezing at near 0 °C

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