Amyloid fibrils are found in a number of neurodegenerative disorders, including Alzheimer's and prion-based diseases. These fibrils are rope-like structures formed by linked protein molecules. David Eisenberg and his colleagues report in the 08 Sept. 2005 issue of Nature (Vol. 436, No. 7056, pp. 266-269) how these proteins can "zip up" without losing their ability to function properly.
The accepted paradigm has been that native proteins undergo wholesale refolding into a generic amyloid structure. Using a 'designer' enzyme that can form amyloids, Eisenberg and his team now show that this model might need modifying. The enzyme simply opens, and the amyloid spine forms from one segment of its polypeptide chain while the core of the protein remains folded. The one polypeptide segment missing after opening can be complemented - through a domain-swap with the neighbouring protein - to form active enzyme again.
"Because of their large size and variable length, amyloid fibres confound traditional methods used to determine protein structure. Sambashivan et al. use an ingenious approach to show that the protein in the fibre has a native structure," writes Andrew Miranker in a related News and Views piece.
David Eisenberg (UCLA, Los Angeles, CA, USA)
Tel: +1 310 825 3754; E-mail: firstname.lastname@example.org
Andrew Miranker (Yale University, New Haven, CT, USA)
Tel: +1 203 432 8954; E-mail: email@example.com
(C) Nature press release.
Message posted by: Trevor M. D'Souza