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(-)-Epigallocatechin-3-gallate (EGCG) maintains k-casein in its pre-fibrillar state without redirecting its aggregation pathway

Journal Article


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Abstract


  • The polyphenol (-)-epigallocatechin-3-gallate (EGCG) has recently attracted much research interest in the field of protein-misfolding diseases because of its potent anti-amyloid activity against amyloid-beta, alpha-synuclein and huntingtin, the amyloid-fibril-forming proteins involved in Alzheimer's, Parkinson's and Huntington's diseases, respectively. EGCG redirects the aggregation of these polypeptides to a disordered off-folding pathway that results in the formation of non-toxic amorphous aggregates. whether this anti-fibril activity is specific to these disease-related target proteins or ismore generic remains to be established. In addition, the mechanism by which EGCG exerts its effects, as with all anti-amyloidogenic polyphenols, remains unclear. To address these aspects, we have investigated the ability of EGCG to inhibit amyloidogenesis of the generic model fibril-forming protein RCMkappa-CN (reduced and carboxymethylated kappa-casein) and thereby protect pheochromocytoma-12 cells from RCMkappa-CN amyloid-induced toxicity. We found that EGCG potently inhibits in vitro fibril formation byRCMkappa-CN [the IC50 for 50 uM RCMkappa-CN is 1 uM]. Biophysical studies reveal that EGCG prevents RCMkappa-CN fibril formation by stabilising RCMkappa-CN in its nativelike state rather than by redirecting its aggregation to the disordered, amorphous aggregation pathway. Thus, while it appears that EGCG is a generic inhibitor of amyloid-fibril formation, the mechanism by which it achieves this inhibition is specific to the target fibril-forming polypeptide. It is proposed that EGCG is directed to the amyloidogenic sheet-turn-sheet motif of monomeric RCMkappa-CN with high affinity by strong non-specific hydrophobic associations. Additional non-covalent pi-pi stacking interactions between the polyphenolic and aromatic residues common to the amyloidogenic sequence are also implicated.

Authors


  •   Hudson, Sean A. (external author)
  •   Ecroyd, Heath
  •   Dehle, Francis C. (external author)
  •   Musgrave, Ian F. (external author)
  •   Carver, John A. (external author)

Publication Date


  • 2009

Citation


  • Hudson, S. A., Ecroyd, H., Dehle, F. C., Musgrave, I. F. & Carver, J. A. (2009). (-)-Epigallocatechin-3-gallate (EGCG) maintains k-casein in its pre-fibrillar state without redirecting its aggregation pathway. Journal of Molecular Biology, 392 (3), 689-700.

Scopus Eid


  • 2-s2.0-69349098271

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1983&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/944

Has Global Citation Frequency


Number Of Pages


  • 11

Start Page


  • 689

End Page


  • 700

Volume


  • 392

Issue


  • 3

Abstract


  • The polyphenol (-)-epigallocatechin-3-gallate (EGCG) has recently attracted much research interest in the field of protein-misfolding diseases because of its potent anti-amyloid activity against amyloid-beta, alpha-synuclein and huntingtin, the amyloid-fibril-forming proteins involved in Alzheimer's, Parkinson's and Huntington's diseases, respectively. EGCG redirects the aggregation of these polypeptides to a disordered off-folding pathway that results in the formation of non-toxic amorphous aggregates. whether this anti-fibril activity is specific to these disease-related target proteins or ismore generic remains to be established. In addition, the mechanism by which EGCG exerts its effects, as with all anti-amyloidogenic polyphenols, remains unclear. To address these aspects, we have investigated the ability of EGCG to inhibit amyloidogenesis of the generic model fibril-forming protein RCMkappa-CN (reduced and carboxymethylated kappa-casein) and thereby protect pheochromocytoma-12 cells from RCMkappa-CN amyloid-induced toxicity. We found that EGCG potently inhibits in vitro fibril formation byRCMkappa-CN [the IC50 for 50 uM RCMkappa-CN is 1 uM]. Biophysical studies reveal that EGCG prevents RCMkappa-CN fibril formation by stabilising RCMkappa-CN in its nativelike state rather than by redirecting its aggregation to the disordered, amorphous aggregation pathway. Thus, while it appears that EGCG is a generic inhibitor of amyloid-fibril formation, the mechanism by which it achieves this inhibition is specific to the target fibril-forming polypeptide. It is proposed that EGCG is directed to the amyloidogenic sheet-turn-sheet motif of monomeric RCMkappa-CN with high affinity by strong non-specific hydrophobic associations. Additional non-covalent pi-pi stacking interactions between the polyphenolic and aromatic residues common to the amyloidogenic sequence are also implicated.

Authors


  •   Hudson, Sean A. (external author)
  •   Ecroyd, Heath
  •   Dehle, Francis C. (external author)
  •   Musgrave, Ian F. (external author)
  •   Carver, John A. (external author)

Publication Date


  • 2009

Citation


  • Hudson, S. A., Ecroyd, H., Dehle, F. C., Musgrave, I. F. & Carver, J. A. (2009). (-)-Epigallocatechin-3-gallate (EGCG) maintains k-casein in its pre-fibrillar state without redirecting its aggregation pathway. Journal of Molecular Biology, 392 (3), 689-700.

Scopus Eid


  • 2-s2.0-69349098271

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=1983&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/944

Has Global Citation Frequency


Number Of Pages


  • 11

Start Page


  • 689

End Page


  • 700

Volume


  • 392

Issue


  • 3