scholarly journals Carrot ‘antifreeze’ protein has an irregular ice-binding site that confers weak freezing point depression but strong inhibition of ice recrystallization

2020 ◽  
Vol 477 (12) ◽  
pp. 2179-2192 ◽  
Author(s):  
Yannan Wang ◽  
Laurie A. Graham ◽  
Zhifu Han ◽  
Robert Eves ◽  
Audrey K. Gruneberg ◽  
...  
Keyword(s):  
Convex Surface ◽  
Freezing Point ◽  
Protein Structures ◽  
Freeze Tolerance ◽  
Antifreeze Protein ◽  
Site Directed Mutagenesis ◽  
Freezing Point Depression ◽  
Freezing Damage ◽  
Ice Recrystallization ◽  
Ice Binding

Ice-binding proteins (IBPs) are found in many biological kingdoms where they protect organisms from freezing damage as antifreeze agents or inhibitors of ice recrystallization. Here, the crystal structure of recombinant IBP from carrot (Daucus carota) has been solved to a resolution of 2.3 Å. As predicted, the protein is a structural homologue of a plant polygalacturonase-inhibiting protein forming a curved solenoid structure with a leucine-rich repeat motif. Unexpectedly, close examination of its surface did not reveal any large regions of flat, regularly spaced hydrophobic residues that characterize the ice-binding sites (IBSs) of potent antifreeze proteins from freeze-resistant fish and insects. An IBS was defined by site-directed mutagenesis of residues on the convex surface of the carrot solenoid. This imperfect site is reminiscent of the irregular IBS of grass ‘antifreeze’ protein. Like the grass protein, the carrot IBP has weak freezing point depression activity but is extremely active at nanomolar concentrations in inhibiting ice recrystallization. Ice crystals formed in the presence of both plant proteins grow slowly and evenly in all directions. We suggest that this slow, controlled ice growth is desirable for freeze tolerance. The fact that two plant IBPs have evolved very different protein structures to affect ice in a similar manner suggests this pattern of weak freezing point depression and strong ice recrystallization inhibition helps their host to tolerate freezing rather than to resist it.

scholarly journals Growth suppression of ice crystal basal face in the presence of a moderate ice-binding protein does not confer hyperactivity

2018 ◽  
Vol 115 (29) ◽  
pp. 7479-7484 ◽  
Author(s):  
Maddalena Bayer-Giraldi ◽  
Gen Sazaki ◽  
Ken Nagashima ◽  
Sepp Kipfstuhl ◽  
Dmitry A. Vorontsov ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Heat Dissipation ◽  
Freezing Point ◽  
Binding Protein ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Basal Face ◽  
Ice Binding ◽  
Ice Binding Protein

Ice-binding proteins (IBPs) affect ice crystal growth by attaching to crystal faces. We present the effects on the growth of an ice single crystal caused by an ice-binding protein from the sea ice microalga Fragilariopsis cylindrus (fcIBP) that is characterized by the widespread domain of unknown function 3494 (DUF3494) and known to cause a moderate freezing point depression (below 1 °C). By the application of interferometry, bright-field microscopy, and fluorescence microscopy, we observed that the fcIBP attaches to the basal faces of ice crystals, thereby inhibiting their growth in the c direction and resulting in an increase in the effective supercooling with increasing fcIBP concentration. In addition, we observed that the fcIBP attaches to prism faces and inhibits their growth. In the event that the effective supercooling is small and crystals are faceted, this process causes an emergence of prism faces and suppresses crystal growth in the a direction. When the effective supercooling is large and ice crystals have developed into a dendritic shape, the suppression of prism face growth results in thinner dendrite branches, and growth in the a direction is accelerated due to enhanced latent heat dissipation. Our observations clearly indicate that the fcIBP occupies a separate position in the classification of IBPs due to the fact that it suppresses the growth of basal faces, despite its moderate freezing point depression.

scholarly journals Discovery of Hyperactive Antifreeze Protein from Phylogenetically Distant Beetles Questions Its Evolutionary Origin

2021 ◽  
Vol 22 (7) ◽  
pp. 3637
Author(s):  
Tatsuya Arai ◽  
Akari Yamauchi ◽  
Ai Miura ◽  
Hidemasa Kondo ◽  
Yoshiyuki Nishimiya ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Tandem Repeats ◽  
Freezing Point ◽  
Consensus Sequence ◽  
Antifreeze Protein ◽  
Ice Crystal ◽  
Freezing Point Depression ◽  
Entire Surface ◽  
Chilled Storage ◽  
Peptide Region

Beetle hyperactive antifreeze protein (AFP) has a unique ability to maintain a supercooling state of its body fluids, however, less is known about its origination. Here, we found that a popular stag beetle Dorcus hopei binodulosus (Dhb) synthesizes at least 6 isoforms of hyperactive AFP (DhbAFP). Cold-acclimated Dhb larvae tolerated −5 °C chilled storage for 24 h and fully recovered after warming, suggesting that DhbAFP facilitates overwintering of this beetle. A DhbAFP isoform (~10 kDa) appeared to consist of 6−8 tandem repeats of a 12-residue consensus sequence (TCTxSxNCxxAx), which exhibited 3 °C of high freezing point depression and the ability of binding to an entire surface of a single ice crystal. Significantly, these properties as well as DNA sequences including the untranslated region, signal peptide region, and an AFP-encoding region of Dhb are highly similar to those identified for a known hyperactive AFP (TmAFP) from the beetle Tenebrio molitor (Tm). Progenitor of Dhb and Tm was branched off approximately 300 million years ago, so no known evolution mechanism hardly explains the retainment of the DNA sequence for such a lo­ng divergence period. Existence of unrevealed gene transfer mechanism will be hypothesized between these two phylogenetically distant beetles to acquire this type of hyperactive AFP.

scholarly journals Freeze Resistance of Pacific Northwest Strawberry Flowers

1997 ◽  
Vol 122 (2) ◽  
pp. 179-182 ◽  
Author(s):  
Rita L. Hummel ◽  
Patrick P. Moore
Keyword(s):  
Pacific Northwest ◽  
Freezing Point ◽  
Freeze Tolerance ◽  
Cultivar Differences ◽  
Freezing Point Depression ◽  
Freeze Avoidance ◽  
Freeze Resistance ◽  
Sources Of Variation ◽  
Freeze Damage ◽  
Spring Frosts

The roles of freeze avoidance and freeze tolerance in determining strawberry (Fragaria ×ananassa) flower freeze resistance were compared in laboratory freeze tests. Genotype, freezing point depression of expressed cell sap, and flower size were examined as potential sources of variation in freeze resistance. When ice was added as a nucleator to excised flowers, mean freeze damage was 97% at -3.0 °C, but in the absence of ice, flowers appeared to supercool and had only 15% damage at -4.0 °C. Without nucleation, cultivar differences in freeze damage were significant in three of four freezing temperatures, but the relative ranking of cultivar freeze damage was not consistent across temperatures. Cultivars that sustained the least amount of injury at -4 °C, were not necessarily the least injured at -7 °C. With an ice nucleator, damage occurred at warmer temperatures (-1.5 °C), but there was no relationship between percentage damage at -1.5 °C with nucleation and -4 °C without nucleation across cultivars. Freezing-point depression of expressed cell sap did not account for the variation in freeze resistance. In nucleated and nonnucleated treatments, larger flowers were more likely to be freeze damaged. Results of this research suggest that flowers of all cultivars are susceptible to freeze damage and survive spring frosts by freeze avoidance.

A Ca2+-dependent bacterial antifreeze protein domain has a novel β-helical ice-binding fold

2008 ◽  
Vol 411 (1) ◽  
pp. 171-180 ◽  
Author(s):  
Christopher P. Garnham ◽  
Jack A. Gilbert ◽  
Christopher P. Hartman ◽  
Robert L. Campbell ◽  
Johanna Laybourn-Parry ◽  
...  
Keyword(s):  
Freezing Point ◽  
Protein Domain ◽  
Site Directed Mutagenesis ◽  
Hydrophobic Core ◽  
Amino Acid Region ◽  
Ice Binding ◽  
Binding Surface ◽  
The Antarctic ◽  
Antifreeze Activity ◽  
Acid Region

AFPs (antifreeze proteins) are produced by many organisms that inhabit ice-laden environments. They facilitate survival at sub-zero temperatures by binding to, and inhibiting, the growth of ice crystals in solution. The Antarctic bacterium Marinomonas primoryensis produces an exceptionally large (>1 MDa) hyperactive Ca2+-dependent AFP. We have cloned, expressed and characterized a 322-amino-acid region of the protein where the antifreeze activity is localized that shows similarity to the RTX (repeats-in-toxin) family of proteins. The recombinant protein requires Ca2+ for structure and activity, and it is capable of depressing the freezing point of a solution in excess of 2 °C at a concentration of 0.5 mg/ml, therefore classifying it as a hyperactive AFP. We have developed a homology-guided model of the antifreeze region based partly on the Ca2+-bound β-roll from alkaline protease. The model has identified both a novel β-helical fold and an ice-binding site. The interior of the β-helix contains a single row of bound Ca2+ ions down one side of the structure and a hydrophobic core down the opposite side. The ice-binding surface consists of parallel repetitive arrays of threonine and aspartic acid/asparagine residues located down the Ca2+-bound side of the structure. The model was tested and validated by site-directed mutagenesis. It explains the Ca2+-dependency of the region, as well its hyperactive antifreeze activity. This is the first bacterial AFP to be structurally characterized and is one of only five hyperactive AFPs identified to date.

Depression of freezing temperature of water and water solutions in porous materials

1989 ◽  
Vol 54 (10) ◽  
pp. 2644-2647 ◽  
Author(s):  
Petr Schneider ◽  
Jiří Rathouský
Keyword(s):  
Water Vapor ◽  
Porous Materials ◽  
Inorganic Salt ◽  
Freezing Point ◽  
Freezing Temperature ◽  
Inorganic Salts ◽  
Freezing Point Depression ◽  
Salt Solutions ◽  
Water Solutions

In porous materials filled with water or water solutions of inorganic salts, water freezes at lower temperatures than under normal conditions; the reason is the decrease of water vapor tension above the convex meniscus of liquid in pores. The freezing point depression is not very significant in pores with radii from 0.05 μm to 10 μm (about 0.01-2.5 K). Only in smaller pores, especially when filled with inorganic salt solutions, this depression is important.

scholarly journals Freezing point depression and freeze-thaw damage by nanofluidic salt trapping

2020 ◽  
Vol 5 (12) ◽  
Author(s):  
Tingtao Zhou ◽  
Mohammad Mirzadeh ◽  
Roland J.-M. Pellenq ◽  
Martin Z. Bazant
Keyword(s):  
Freezing Point ◽  
Freezing Point Depression ◽  
Freeze Thaw
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