A de novo designed helix-turn-helix peptide forms nontoxic amyloid fibrils.
We report here that a monomeric de novo designed alpha-helix-turn-alpha-helix peptide, alpha t alpha, when incubated at 37 degrees C in an aqueous buffer at neutral pH, forms nonbranching, protease resistant fibrils that are 6-10 nm in diameter. These fibrils are rich in beta-sheet and bind the amyloidophilic dye Congo red. alpha t alpha fibrils thus display the morphologic, structural, and tinctorial properties of authentic amyloid fibrils. Surprisingly, unlike fibrils formed by peptides such as the amyloid beta-protein or the islet amyloid polypeptide, alpha t alpha fibrils were not toxic to cultured rat primary cortical neurons or PC12 cells. These results suggest that the potential to form fibrils under physiologic conditions is not limited to those proteins associated with amyloidoses and that fibril formation alone is not predictive of cytotoxic activity.
Fezoui
Y
Y
Department of Neurology (Neuroscience), Harvard Medical School, Boston, Massachusetts 02115, USA. fezouli@cnd.bwh.harvard.edu
Hartley
D M
DM
Walsh
D M
DM
Selkoe
D J
DJ
Osterhout
J J
JJ
Teplow
D B
DB
D000595:Amino Acid Sequence; D000818:Animals; D001704:Biopolymers / Q000737:chemistry / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002942:Circular Dichroism; D003224:Congo Red; D019286:Endopeptidase K / Q000378:metabolism; D005562:Formazans; D019077:Helix-Turn-Helix Motifs; D006863:Hydrogen-Ion Concentration; D008854:Microscopy, Electron; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000187:drug effects; D016716:PC12 Cells; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism* / Q000633:toxicity; D058225:Plaque, Amyloid / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D011487:Protein Conformation; D051381:Rats; D055672:Static Electricity; D013778:Tetrazolium Salts
D001704:Biopolymers; D005562:Formazans; D010455:Peptides; D013778:Tetrazolium Salts; C079782:MTT formazan; D003224:Congo Red; D019286:Endopeptidase K