Rapid amyloid fiber formation from the fast-folding WW domain FBP28.
The WW domains are small proteins that contain a three-stranded, antiparallel beta-sheet. The 40-residue murine FBP28 WW domain rapidly formed twirling ribbon-like fibrils at physiological temperature and pH, with morphology typical of amyloid fibrils. These ribbons were unusually wide and well ordered, making them highly suitable for structural studies. Their x-ray and electron-diffraction patterns displayed the characteristic amyloid fiber 0.47-nm reflection of the cross-beta diffraction signature. Both conventional and electron cryomicroscopy showed clearly that the ribbons were composed of many 2.5-nm-wide subfilaments that ran parallel to the long axis of the fiber. There was a region of lower density along the center of each filament. Lateral association of these filaments generated twisted, often interlinked, sheets up to 40 nm wide and many microns in length. The pitch of the helix varied from 60 to 320 nm, depending on the width of the ribbon. The wild-type FBP28 fibers were formed under conditions in which multiexponential folding kinetics is observed in other studies and which was attributed to a change in the mechanism of folding. It is more likely that those phases result from initial events in the off-pathway aggregation observed here.
Ferguson
Neil
N
Medical Research Council Centre for Protein Engineering, Medical Research Council Centre, Hills Road, Cambridge CB2 2QH, UK.
Berriman
John
J
Petrovich
Miriana
M
Sharpe
Timothy D
TD
Finch
John T
JT
Fersht
Alan R
AR
D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D066298:In Vitro Techniques; D007700:Kinetics; D008027:Light; D046911:Macromolecular Substances; D051379:Mice; D008854:Microscopy, Electron; D008958:Models, Molecular; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012542:Scattering, Radiation; D035602:Transcriptional Elongation Factors; D014961:X-Ray Diffraction
D000682:Amyloid; D002352:Carrier Proteins; D046911:Macromolecular Substances; C473940:Tcerg1 protein, mouse; D035602:Transcriptional Elongation Factors