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Transient aggregation and stable dimerization induced by introducing an Alzheimer sequence into a water-soluble protein

Otzen, D E; Miron, Simona; Akke, Mikael LU and Oliveberg, M (2004) In Biochemistry 43(41). p.12964-12978
Abstract
Transient contacts between denatured polypeptide chains are likely to play an important part in the initial stages of protein aggregation and fibrillation. To analyze the nature of such contacts, we have carried out a protein engineering study of the 102-residue protein U1A, which aggregates transiently in the wild-type form during refolding from the guanidinium chloride-denatured state. We have prepared a series of mutants with increased aggregation tendencies by increasing the homology between two beta-strands of U1A and the Alzheimer peptide beta-AP. These mutants undergo transient aggregation during refolding, as measured by concentration dependence, double-jump experiments, and binding of ANS, a probe for exposed hydrophobic patches... (More)
Transient contacts between denatured polypeptide chains are likely to play an important part in the initial stages of protein aggregation and fibrillation. To analyze the nature of such contacts, we have carried out a protein engineering study of the 102-residue protein U1A, which aggregates transiently in the wild-type form during refolding from the guanidinium chloride-denatured state. We have prepared a series of mutants with increased aggregation tendencies by increasing the homology between two beta-strands of U1A and the Alzheimer peptide beta-AP. These mutants undergo transient aggregation during refolding, as measured by concentration dependence, double-jump experiments, and binding of ANS, a probe for exposed hydrophobic patches on protein surfaces. The propensity to aggregate increases with increasing homology to beta-AP. Further, the degree of transient ANS binding correlates reasonably well with the structural parameters recently shown to play a role in the fibrillation of natively unfolded proteins. Two mutants highly prone to transient aggregation, U1A-J and U1A-G, were also studied by NMR. Secondary structural elements of the U1A-J construct (with lower beta-AP homology) are very similar to those observed in U1A-wt. In contrast, the high-homology construct U1A-G exhibits local unfolding of the C-terminal helix, which packs against the beta-sheet in the wild-type protein. U1A-G is mainly dimeric according to N-15 spin relaxation data, and the dimer interface most likely involves the beta-sheet. Our data suggest that the transient aggregate relies on specific intermolecular interactions mediated by structurally flexible regions and that contacts may be formed in different beta-strand registers. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
43
issue
41
pages
12964 - 12978
publisher
The American Chemical Society
external identifiers
  • wos:000224463000002
  • scopus:5444246037
ISSN
0006-2960
DOI
10.1021/bi048509k
language
English
LU publication?
yes
id
5ecc076a-dbfa-4275-acb1-87d58c154bd5 (old id 141068)
date added to LUP
2007-06-29 14:11:48
date last changed
2017-01-01 05:16:57
@article{5ecc076a-dbfa-4275-acb1-87d58c154bd5,
  abstract     = {Transient contacts between denatured polypeptide chains are likely to play an important part in the initial stages of protein aggregation and fibrillation. To analyze the nature of such contacts, we have carried out a protein engineering study of the 102-residue protein U1A, which aggregates transiently in the wild-type form during refolding from the guanidinium chloride-denatured state. We have prepared a series of mutants with increased aggregation tendencies by increasing the homology between two beta-strands of U1A and the Alzheimer peptide beta-AP. These mutants undergo transient aggregation during refolding, as measured by concentration dependence, double-jump experiments, and binding of ANS, a probe for exposed hydrophobic patches on protein surfaces. The propensity to aggregate increases with increasing homology to beta-AP. Further, the degree of transient ANS binding correlates reasonably well with the structural parameters recently shown to play a role in the fibrillation of natively unfolded proteins. Two mutants highly prone to transient aggregation, U1A-J and U1A-G, were also studied by NMR. Secondary structural elements of the U1A-J construct (with lower beta-AP homology) are very similar to those observed in U1A-wt. In contrast, the high-homology construct U1A-G exhibits local unfolding of the C-terminal helix, which packs against the beta-sheet in the wild-type protein. U1A-G is mainly dimeric according to N-15 spin relaxation data, and the dimer interface most likely involves the beta-sheet. Our data suggest that the transient aggregate relies on specific intermolecular interactions mediated by structurally flexible regions and that contacts may be formed in different beta-strand registers.},
  author       = {Otzen, D E and Miron, Simona and Akke, Mikael and Oliveberg, M},
  issn         = {0006-2960},
  language     = {eng},
  number       = {41},
  pages        = {12964--12978},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {Transient aggregation and stable dimerization induced by introducing an Alzheimer sequence into a water-soluble protein},
  url          = {http://dx.doi.org/10.1021/bi048509k},
  volume       = {43},
  year         = {2004},
}