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Perplexing cooperative folding and stability of a low-sequence complexity, polyproline 2 protein lacking a hydrophobic core

Title
Perplexing cooperative folding and stability of a low-sequence complexity, polyproline 2 protein lacking a hydrophobic core
Authors
Gates, Zachary P.Baxa, Michael C.Yu, WookyungRiback, Joshua A.Li, HuiRoux, BenoitKent, Stephen B. H.Sosnick, Tobin R.
DGIST Authors
Yu, Wookyung
Issue Date
2017-02-28
Citation
Proceedings of the National Academy of Sciences of the United States of America, 114(9), 2241-2246
Type
Article
Article Type
Conference Paper
Keywords
BackboneCollapseCooperativityCooperativityFlea Antifreeze ProteinFree EnergyHydrogen BondsHydrogen BondingHydrogen BondingKineticsKineticsMolecular DynamicsNonnative InteractionsPotential FunctionsPP2Protein FoldingProtein FoldingTransition StateUnfolded Proteins
ISSN
0027-8424
Abstract
The burial of hydrophobic side chains in a protein core generally is thought to be the major ingredient for stable, cooperative folding. Here, we show that, for the snow flea antifreeze protein (sfAFP), stability and cooperativity can occur without a hydrophobic core, and without α-helices or β-sheets. sfAFP has low sequence complexity with 46% glycine and an interior filled only with backbone H-bonds between six polyproline 2 (PP2) helices. However, the protein folds in a kinetically two-state manner and is moderately stable at room temperature. We believe that a major part of the stability arises from the unusual match between residue-level PP2 dihedral angle bias in the unfolded state and PP2 helical structure in the native state. Additional stabilizing factors that compensate for the dearth of hydrophobic burial include shorter and stronger H-bonds, and increased entropy in the folded state. These results extend our understanding of the origins of cooperativity and stability in protein folding, including the balance between solvent and polypeptide chain entropies.
URI
http://hdl.handle.net/20.500.11750/4232
DOI
10.1073/pnas.1609579114
Publisher
National Academy of Sciences
Related Researcher
  • Author Yu, Woo Kyung Laboratory of Protein Biophysics
  • Research Interests protein biophysics; protein folding; protein dynamics and conformational change
Files:
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Collection:
Brain and Cognitive SciencesETC1. Journal Articles


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