6W78

crystal structure of a plant ice-binding protein

6W78 の概要

• エントリーDOI: 10.2210/pdb6w78/pdb
• 分子名称: Antifreeze polypeptide, 2-acetamido-2-deoxy-beta-D-glucopyranose (3 entities in total)
• 機能のキーワード: antifreeze protein, ice-binding, ice recrystallization inhibition
• 由来する生物種: Daucus carota (Wild carrot)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 37602.88

構造登録者

Wang, Y.N.,Zhang, H.Q. (登録日: 2020-03-18, 公開日: 2021-01-20, 最終更新日: 2024-10-23)

主引用文献

Wang, Y.,Graham, L.A.,Han, Z.,Eves, R.,Gruneberg, A.K.,Campbell, R.L.,Zhang, H.,Davies, P.L.
Carrot 'antifreeze' protein has an irregular ice-binding site that confers weak freezing point depression but strong inhibition of ice recrystallization.
Biochem.J., 477:2179-2192, 2020

PubMed Abstract: 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.

PubMed: 32459306
DOI: 10.1042/BCJ20200238

実験手法

X-RAY DIFFRACTION (2.311 Å)