An Antifreeze Protein Folds with an Interior Network of More Than 400 Semi-Clathrate Waters
When polypeptide chains fold into a protein, hydrophobic groups are compacted in the center with exclusion of water. We report the crystal structure of an alanine-rich antifreeze protein that retains ~400 waters in its core. The putative ice-binding residues of this dimeric, four-helix bundle protein point inwards and coordinate the interior waters into two intersecting polypentagonal networks. The bundle makes minimal protein contacts between helices, but is stabilized by anchoring to the semi-clathrate water monolayers through backbone carbonyl groups in the protein interior. The ordered waters extend outwards to the protein surface and likely are involved in ice binding. This protein fold supports both the anchored-clathrate water mechanism of antifreeze protein adsorption to ice and the water-expulsion mechanism of protein folding.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- OSTI ID:
- 1354261
- Report Number(s):
- BNL--112777-2016-JA
- Journal Information:
- Science, Journal Name: Science Journal Issue: 6172 Vol. 343; ISSN 0036-8075
- Publisher:
- AAAS
- Country of Publication:
- United States
- Language:
- English
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