The effects of aggregation-inducing motifs on amyloid formation of model proteins related to neurodegenerative diseases.
To examine the effects of aggregation-inducing motifs related to neurodegenerative diseases on amyloid formation of host protein, we prepared several chimera myoglobins, in which various aggregation-inducing motifs were inserted. The focused aggregation-inducing motifs included five (R5) or two (R2) oligopeptide repeats in yeast Sup35p, five octapeptide repeats (OPR) in the human prion protein, a nonamyloid beta component (NAC) in alpha-synuclein, and tandem repeats of 50 glutamines (Q50). Circular dichroism and infrared spectroscopies suggested that the OPR, R5, and Q50 motifs formed an antiparallel beta sheet as well as a random coil, whereas the R2 and NAC motifs mainly formed random coils. The OPR, R5, and Q50 mutants, but not the R2 and NAC mutants, readily formed the SDS-resistant aggregates under physiological condition, and electron microscopy revealed that the aggregates contained amyloid fibrils. The destabilization and increase in gyration radius of the OPR, R5, and Q50 mutants correlated with the tendency to form amyloid fibrils. A control mutant bearing a nonamyloidgenic sequence was also moderately destabilized but did not form amyloid fibrils. Therefore, we concluded that the OPR, R5, and Q50 motifs, even in a quite stable protein such as myoglobin, led the host protein to formation of amyloid fibrils under physiological condition.
Tanaka
Motomasa
M
Laboratory for CAG Repeat Diseases, RIKEN Brain Science Institute, Saitama 351-0198, Japan.
Machida
Yoko
Y
Nishikawa
Yukihiro
Y
Akagi
Takumi
T
Morishima
Isao
I
Hashikawa
Tsutomu
T
Fujisawa
Tetsuro
T
Nukina
Nobuyuki
N
D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D000818:Animals; D002942:Circular Dichroism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009211:Myoglobin / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics; D019636:Neurodegenerative Diseases / Q000378:metabolism* / Q000473:pathology; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000737:chemistry / Q000235:genetics; D010454:Peptide Termination Factors; D011328:Prions / Q000737:chemistry / Q000235:genetics; D011489:Protein Denaturation / Q000235:genetics; D015202:Protein Engineering; D017433:Protein Structure, Secondary / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000648:ultrastructure; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017550:Spectroscopy, Fourier Transform Infrared; D051843:Synucleins; D014907:Whales; D051844:alpha-Synuclein
D000682:Amyloid; D005656:Fungal Proteins; D009211:Myoglobin; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D010454:Peptide Termination Factors; D011328:Prions; D011993:Recombinant Fusion Proteins; C497604:SNCA protein, human; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D051843:Synucleins; D051844:alpha-Synuclein