Cystatin forms a tetramer through structural rearrangement of domain-swapped dimers prior to amyloidogenesis.

Abstract

The cystatins were the first amyloidogenic proteins to be shown to oligomerize through a 3D domain swapping mechanism. Here we show that, under conditions leading to the formation of amyloid deposits, the domain-swapped dimer of chicken cystatin further oligomerizes to a tetramer, prior to fibrillization. The tetramer has a very similar circular dichroism and fluorescence signature to the folded monomer and dimer structures, but exhibits some loss of dispersion in the 1H-NMR spectrum. 8-Anilino-1-naphthalene sulfonate fluorescence enhancement indicates an increase in the degree of disorder. While the dimerization reaction is bimolecular and most likely limited by the availability of a predominantly unfolded form of the monomer, the tetramerization reaction is first-order. The tetramer is formed slowly (t(1/2)=six days at 85 degrees C), dimeric cystatin is the precursor to tetramer formation, and thus the rate is limited by structural rearrangement within the dimer. Some higher-order oligomerization events parallel tetramer formation while others follow from the tetrameric form. Thus, the tetramer is a transient intermediate within the pathway of large-scale oligomerization.

• Authors: Anna Sanders, C Jeremy Craven, Lee D Higgins, Silva Giannini, Matthew J Conroy, Andrea M Hounslow, Jonathan P Waltho, Rosemary A Staniforth
• Journal: Journal of molecular biology (J Mol Biol) Vol. 336 Issue 1 Pg. 165-78 (Feb 06 2004) ISSN: 0022-2836 [Print] Netherlands
• PMID: 14741212 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amyloid
• Cystatins
• Recombinant Proteins

Topics

• Amyloid (chemistry, metabolism)
• Animals
• Chickens
• Cystatins (chemistry, metabolism)
• Dimerization
• Humans
• Models, Molecular
• Molecular Weight
• Protein Folding
• Protein Structure, Quaternary
• Recombinant Proteins (chemistry, metabolism)