NR ASKM
AU Modler,A.J.; Fabian,H.; Sokolowski,F.; Lutsch,G.; Gast,K.; Damaschun,G.
TI Polymerization of proteins into amyloid protofibrils shares common critical oligomeric states but differs in the mechanisms of their formation
QU Amyloid 2004 Dec; 11(4): 215-31
PT journal article
AB Amyloid protofibril formation of phosphoglycerate kinase (PGK) and Syrian hamster prion protein (SHaPrP(90-232)) were investigated by static and dynamic light scattering, size exclusion chromatography and electron microscopy. Changes in secondary structure were monitored by Fourier transform infrared spectroscopy and by circular dichroism. Protofibril formation of the two proteins is found to be a two-stage process. At the beginning, an ensemble of critical oligomers is built up. These critical oligomeric states possess a predominant beta-sheet structure and do not interact considerably with monomers. Initial oligomerization and transition to beta-sheet structure are coupled events differing in their details for both proteins. Intermediate oligomeric states (dimers, trimers, etc.) are populated in case of PGK, whereas SHaPrP(90-232) behaves according to an apparent two-state reaction between monomers and octamers rich in beta-structure with a reaction order varying between 2 and 4. All oligomers coalesce to PGK protofibrils in the second stage, while SHaPrP(90-232) protofibrils are only formed by a subpopulation. The rates of both growth stages can be tuned in case of PGK by different salts preserving the underlying generalized diffusion-collision mechanism. The different kinetics of the early misfolding and oligomerization events of the two proteins argue against a common mechanism of protofibril formation. A classification scheme for misassembly mechanisms of proteins based on energy landscapes is presented. It includes scenarios of downhill polymerization to which protofibril formation of PGK and SHaPrP(90-232) belong.
MH Amyloid/*chemistry/ultrastructure; Animals; Circular Dichroism; Hamsters; Kinetics; Microscopy, Electron; Phosphoglycerate Kinase/*chemistry/ultrastructure; Prions/*chemistry/ultrastructure; Protein Structure, Secondary; Research Support, Non-U.S. Gov't; Spectrophotometry, Infrared
AD Max-Delbruck-Centrum fur Molekulare Medizin, Robert-Rossle-Str 10, D-13125 Berlin, Germany. Andreas.Modler@gmx.de
SP englisch
PO USA